Early 2011 MacBook Pro 17" to 30" cinema display

Question: I have a 17" MacBook Pro and a 30" Apple cinema display.  The best resolution I can get on the cinema display is 1280x800.  Is there a way to get better resolution?
Comment: Both your MBP and Display are capable of 2560 by 1440 pixels resolution.  What have you tried that doesn't work?
Comment: What video connections are you using? What vintage of MBP 17" do you own. The last 17" MBP (Early '11) had Thunderbolt DV out (capable of 2 T-bolt ext displays); whilst the first 17" MBP ('06) had a Dual-link DVI.
Answer: Your particular model of MacBook Pro was equipped with an AMD Radeon HD 6750M dedicated graphics card and on-board Intel HD 3000 graphics card. In terms of VRAM you have 1 GB available on the AMD and 384 MB on the Intel (shared with main memory).
This combination is capable of up to 2560 x 1600 pixels on external displays that do not require a dual-link DVI connection.
If you're finding that the highest available resolution is 1280 x 800 instead of 2560 x 1600, this is likely due to you using a single-link DVI connection on a display that requires a dual-link DVI connection. Unfortunately, the 30" Apple Cinema Display is one such monitor.
You would need to connect this display to a dual-link DVI port to access the higher resolutions available on the 30" display. However, your model MacBook Pro does not provide a dual-link DVI connection without an appropriate adaptor and that is why it's not supporting the 30" Apple Cinema Display at its native 2560 x 1600 resolution.
For best results you will need to use a Mini DisplayPort to Dual-Link DVI adapter.
You should refer to this info on Apple's website. Also of interest may be this Mini DisplayPort adapter FAQs page.


How to slow down while maintaining altitude

Question: Is reducing throttle/power already enough? Or do I have to adjust the pitch as well? If so, I suppose pitching up as well? If pitching up is needed as well, is it because as speed decrease, there is less aerodynamic force acting on the tail and so the tail down force is less which pitch the nose down? Or is it because as speed decrease, lift decrease, so pitch up to create more lift?
Answer: To maintain altitude, lift must be equal to weight. The first question is, does slowing down reduce the amount of lift we have?
We can look at the lift formula for the answer:
$$\mbox{Lift} = C_l \times 0.5 \times \rho \times V^2 \times S$$
Airspeed is a part of this formula, represented by V. Therefore we can say that if we slow down, we will have a reduction in lift and therefore descend, if we don't change anything else.
So what can we change to maintain altitude? Working from the end of the formula: S can be increased with flap in some aircraft, but this is inefficient and cumbersome. Then, ρ is air density which is outside of our control. That leaves Cl, which is essentially a function of camber and angle of attack.
Again, camber could be increased with flap, but the best way to increase Cl is to increase our angle of attack. We can increase this via a pitch adjustment. So there we have our answer - if we want to maintain altitude while slowing down, we must either increase flap or, the preferred option, increase our angle of attack via an increased pitch attitude.
Answer: Consider the four forces acting on an aircraft in equilibrium:

Drag must exceed thrust in order to decelerate.  Presuming that you don't have speed brakes to increase drag, the only way to slow down while keeping lift and weight equal is to reduce thrust.
As the aircraft slows, the wing will produce less lift, requiring an increase in AOA to maintain lift equal to weight.  This will further increase induced drag, necessitating a power correction once the target airspeed is reached.
Comment: @quietflyer, I changed to "power correction".  But... unless you know the exact power setting for your new target airspeed you will likely need to add more power than what was used to decel.  That's what I meant, not that the power would be higher than the first, faster speed.
Comment: Re "necessitating a power addition once the target airspeed is reached."  -- not if initial and final speeds are on the "front side of the power curve".
Answer: If you reduce forward thrust then you implicitly reduce the lift generated by the wing in its current configuration. So to maintain altitude you must pitch up or otherwise change the configuration of the wing - which in itself will change the attitude.
Answer:
Is reducing throttle/power already enough? Or do I have to adjust the
pitch as well?

It depends on the aircraft.  It also depends on whether you are flying on the "front side" or the "back side" of the power curve.
If you are flying on the back side of the power curve, you are going to need to increase power to maintain altitude after you slow to your desired airspeed.
As for pitch inputs--
Most aircraft, at least to a first approximation, have reasonably strong speed stability, meaning that they tend to maintain the trimmed airspeed, even as the engine power output is changed.  This is a secondary result of their tendency to maintain the trimmed angle-of-attack.  So normally, if we are trimmed for some given airspeed, we expect to have to exert some forward pressure on the stick or yoke to maintain a faster airspeed, and we expect to have to exert some aft pressure on the stick or yoke to maintain a slower airspeed-- especially if power is held constant.
But a closer look will reveal that many aircraft have some tendency to move toward a higher angle-of-attack (and a lower airspeed) as power is increased, and a lower angle-of-attack (and a higher airspeed) as power is decreased.  Most high-winged aircraft with tractor (front-mounted) engines fall into this category.
In such case, if you operating deep on the "back side" of the power curve, if you start out trimmed for level flight, it's conceivable that you might have to apply some forward pressure on the stick or yoke as you increase power after slowing down, to maintain your new target airspeed.
Some other aircraft--especially some with engines mounted on a pylon above the fuselage-- have some tendency to move toward a lower angle-of-attack (and a higher airspeed) as power is increased, and a higher angle-of-attack (and a lower airspeed) as power is decreased.
In such case, if you are operating on the "front side" of the power curve, if you start out trimmed for level flight, you'll likely have to apply some forward pressure on the stick or yoke in order to maintain your new target airspeed, after you decrease power to slow down.
But if you are just asking about the aircraft's pitch attitude-- slower flight is almost always associated with an increase in angle-of-attack.1  If the flight path remains horizontal, the aircraft's pitch attitude will always be shifted in the nose-up direction.
Footnotes:

Why "almost"?  Consider this "outlier" case-- "hovering" flight.  Google "model airplane 3-D hover" if you've never seen something shaped like a "conventional" airplane, with no rotor blades or vectored thrust capability, hang on the prop in a stationary zero-airspeed hover.  Here the pitch attitude is 90 degrees, but the angle-of-attack of the wing in relation to the total airflow (including the propwash) is zero degrees (or if the airfoil is non-symmetrical, whatever slight negative angle-of-attack is associated with zero lift.)  Nearly the same applies to flight at extremely low airspeeds, well below stall speed, where the plane is "creeping" slowly along in an extreme nose-high pitch attitude.  It appears to be the case that no full-sized aircraft lacking vectored thrust, rotors, etc can be flown in this manner at present.
Comment: "*If you are flying on the back side of the power curve, you are going to need to increase power to maintain altitude as you slow down.*"  I'd suggesting rewording slightly to avoid reading like you need to add power to slow down. You must **first decrease power** to initiate the slow down, **then add more power** to maintain *airspeed* given the higher AOA needed to maintain *altitude*.
Comment: @MichaelHall -- thanks, done
Comment: Let me know what you think of my edit.  (again, the 4 forces... power counters drag, not weight)
Comment: @MichaelHall -- I decided to roll it back.  The edited statement is not necessarily incorrect, but I find it more natural to think of using pitch inputs to control *airspeed* and power changes to control *vertical speed*.  Especially on the "back side" of the power curve.
Comment: Ok, I agree when flying an approach, but all trimmed up during cruise do you really adjust throttle to hold altitude?  How much time do you really spend on the backside?
Answer:
is reducing power enough, or do I have to adjust the pitch as well?

The pilot is generally ready to do both at the same time, but it helps to know pitch (angle of attack) and power requirements beforehand.
Dig into your Pilots Operating Handbook and find V min power.  This is the airspeed your plane uses the least amount of throttle in level flight (for a given flaps setting).
Any airspeed faster than this will require more power.
If your V min power for flaps zero (clean) is 60 knots, and airspeed is being reduced from 100 knots to 80 knots, you will simultaneously reduce power and pitch up to hold altitude, then re-trim for the new airspeed.
Comment: This is actually similar to what is done at the end of the downwind leg for recreational aircraft, where airspeed is reduced from pattern speed to approach speed.
Answer: Pitch for speed.  Throttle for rate of climb.
So, first you adjust your pitch trim to achieve the desired speed.  Then observe the rate of climb indicator.  If positive (most likely), then decrease throttle to reduce to zero.
Comment: **Comments have been [moved to chat](https://chat.stackexchange.com/rooms/148183/discussion-on-answer-by-rob-mcdonald-how-to-slow-down-while-maintaining-altitude); please do not continue the discussion here.** Before posting a comment below this one, please review the [purposes of comments](/help/privileges/comment). Comments that do not request clarification or suggest improvements usually belong as an [answer](/help/how-to-answer), on [meta], or in [chat]. Comments continuing discussion may be removed.
Comment: This is correct if one is flying on the backside of the power curve.  Here it is safer to pitch up first to desired airspeed.  Chopping throttle first in slow flight and pitching up can easily lead to a stall.


Magento2: what is the difference between layout and page_layout?

Question: As I dig deeper in Magento 2, I noticed that there are layout and page_layout file? What are the differences between the two?
Answer: Well if i put this in simple words than
page_layout represents the full page, i mean you can declare your own full page without inheriting any master or root or other empty layout. (only use, if you want to completely customize your own full page.)
layout represents the part of the page (mostly the html content).  You can use this when you want your page to inherit the common contents from the root layout like header, footer etc etc.
Answer: Layout XML is a tool to build the pages of the Magento application in a modular and flexible manner. It enables us to describe the page layout and content placement.
Looking at XML root nodes, we differentiate two types of layouts:
1. layout: XML wrapped in <layout>
2. page: XML wrapped in <page>

Page layouts represent a full page in HTML, whereas layout layouts represent a part of a page.
The layout type is a subset of the page layout type. Both types of layout XML files are validated by the XSD schema found under the vendor/magento/framework/View/Layout/etc/ directory:
1. layout – layout_generic.xsd
2. page – page_configuration.xsd

Based on the application components that provide  and  elements, we can further section them as base and theme layouts.
The base layouts are provided by the modules, usually at the following locations:
1. <module_dir>/view/frontend/layout: page configuration and generic layout files
2. <module_dir>/view/frontend/page_layout: page layout files

The theme layouts are provided by the themes, usually at the following locations:
1. <theme_dir>/<Namespace>_<Module>/layout: page configuration and generic
layout files
2. <theme_dir>/<Namespace>_<Module>/page_layout: page layout files

Magento will load and merge all module and theme XML files on the appropriate page.
Once files are merged and XML instructions are processed, the result is rendered and sent
to the browser for display.
Answer: Page layout declares the wireframe of a page inside the  section, for example one-column layout or two-column layout.
Allowed layout instructions:
 <container>
 <referenceContainer>
 <move>
 <update>

Generic layouts define the contents and detailed structure inside the  section of the HTML page markup.
Conventionally generic layout files must be located as follows:
Module generic layouts: <module_dir>/view/frontend/layout
Theme generic layouts: <theme_dir>/<Namespace>_<Module>/layout

Follow this link for overview of layout overview: http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/layout-overview.html
And some more detailed information about the layout file types: http://devdocs.magento.com/guides/v2.0/frontend-dev-guide/layouts/layout-types.html


How to create dummy data in a newly created developer org

Question: Is there any automation where we can create dummy data for a newly created org. If i have a excel sheet with multiple sheets in it. Like Account, Contact, Opportunity can we import it.
Comment: Is this a new sandbox for an existing org or a completely new Org? If it is completely new you only have the option of importing the data from Excel by saving into .csv files for each tab then using Data Loader or the Data Import wizard to load it.
Comment: And if it is for existing org how to automate it..
Comment: Have a look at the Answer Mihai provided, also Full Copy sandbox automatically takes all data from production or Partial Copy sandbox can take a snapshot of some production data. Otherwise you are pretty much stuck with uploading even if you automate the upload.
Answer: You could take advantage of the new feature to run a script when a sandbox is created or refreshed. You can find details about the feature in the latest release notes. I would run some apex code that will insert generic accounts or contacts or call an external system that has that spreadsheet uploaded or even a database.
Comment: How to use Run Script After Sandbox Creation and Refresh for creating accounts, contacts and opportunity.. Can u share some code if u hv..
Comment: I don't have any example of a code. But if you look at the release notes, there is an example. You then need to create an Apex class that creates 100 Account, then 200 Contacts and link them and so on. It's basically Apex, and inserting Accounts and Contacts
Comment: Hi, where we need to write the interface..
Comment: It will be on the class you specify in the user interface that will be run as part of the post copy event


I was offered a project management job recently but I realized the products they are building do not have market value, how can I handle this?

Question: The product they are building is for the healthcare system with the major target on healthcare workers. They are focused on communication, collaboration and scheduling.
Comment: This question was migrated because it's  really more about how to evaluate a potential job than it is about project management, or the Product Owner role within a given project management framework.
Comment: There is a niche market in healthcare for smaller EHR and patient management platforms. Competitors like Oracle and Epic control about 60% of the market together but are focused on multi-practice organizations and cost millions plus. Some platforms have traction as they layer into existing platforms. Sounds like you should eval for market position and target audience as well.
Answer: There are a few things to consider:

Will the lack of market value reduce the viability of the company and hence reduce your job security?
Does the lack of market value reduce your passion and enthusiasm for the work?
Does the lack of market value imply some fundamental issues with how the company is run (in that they are trying to build something that likely won't sell)?

I would suggest raising these concerns with somebody at the company. If they can put your mind at rest, then you should feel confident to proceed with the role.
Answer: Your realization is out of scope...unless part of your scope is to refresh its business case. I suspect it's not, so what you realize or don't realize is irrelevant. And if you spent time doing the market research you would need to do to determine a product's viability in the marketplace, I would not bill your customer for that time and effort. Again, because that work is out of scope.
Just build the product and deliver it.
Comment: I don't get why this was downvoted. David is on spot. As a *project* manager, your work is to deliver the project. If the position was for product manager, then the answer would be different. Maybe the downvote comes from a semantic confusion?
Comment: That could be it indeed, David. I don't get this eager we see in IT to catalyse the semantic diffusion of our terminology.
Comment: There is a movement to expand the importance of project management higher than managing the project. It's been going on for years. I reject the entire movement but I suspect the down vote came from someone who wants the pm to be on a higher status.


camera problem in iphone sdk

Question: i would like to open camera in my tab bar app..
i have open the camera but i could not taken the picture because i didnt find the camera symbol in that screen so please tell me how i can i show the camera button(for capture) in camera view? i am also tested it in my iPhone. camera opened but i could not find any button to pick the image.. how can i got if?
Thank You..
code is
<code>picker = [[UIImagePickerController alloc] init];

picker.delegate = self;

picker.sourceType = UIImagePickerControllerSourceTypeCamera;

[Delegate presentModalViewController:picker animated:YES];
</code>
Answer: use
<code>       [self presentModalViewController:picker animated:YES];
</code>
instead of
<code>  [Delegate presentModalViewController:picker animated:YES];
</code>

camera problem in iphone sdk


Phase shift/ cosine within Differential equation (Oscillation).

Question: For instance consider one arbitrary solution of a Differential equation:
$$x_1 = {C_1}'\,e^{-\gamma\,t + i\,\omega\,t} + {C_2}'\,e^{-\gamma\,t-i\,\omega\,t}$$

$\left[\textsf{this is the Solution of $\ddot{x}_1(t)+ 2\,\gamma\,\dot{x}_1(t)+{w_0}^2\,x_1(t) = 0$ where $\omega = \sqrt{{w_0}^2-\gamma^2}$}\right]$

I took it for granted you can only rewrite it like:
$$ \begin{align}&x_1 = ({C_1}'+{C_2}')\,\cos(\omega\,t) + i\,({C_1}'-{C_2}')\,\sin(\omega\,t) \\[12pt]
&x_1= C_1\,\cos(\omega\,t)+C_2\sin(\omega\,t)\end{align}$$
Apparently it is possible to write instead $$x_1 = B_1\,\cos(\omega\,t+\varphi)$$
Is this due to some kind of addition theorems? I'm really bad at those, so don't right see the connection. The reason being I've seen this often recently I need some clarification.

Edit
Actually I found an attempt to the problem in my tattered documents:
Write $C_1 = c\,e^{i\,\varphi}$ and $C_2 = c\,e^{-i\,\varphi}$ (complex constant in polar form)
Hence the solution becomes: $$\begin{align}
&x_1 = c\,e^{i\,\varphi}\,e^{-\gamma\,t + i\,\omega\,t} + c\,e^{-i\,\varphi}\,e^{-\gamma\,t-i\,\omega\,t} \\\\
&x_1 = c\,e^{-\gamma\,t}\,\left(\,e^{i\,(\varphi+\omega\,t)}+\,e^{-i\,(\varphi+\omega\,t)}\right) \\\\
&\text{importantly: $\cos(x) = \dfrac{e^{i\,x}+e^{-i\,x}}{
2}$} \\\\
& \quad\Rightarrow \quad x_1 = 2\,c\,e^{-\gamma\,t}\,\cos(\varphi+\omega\,t) \\\\\\
&\text{Also $2\,c$ can be renamed to "$B_1$" e.g.}
\end{align}$$
My only problem remaining is how $C_1$ and $C_2$ both have same magnitude $c$. So it seems to work only if $C_1$ and $C_2$ are complex conjugate.
Comment: Do you remember the formula for $\cos(A+B)?$
Comment: $\cos(A+B) = \cos(A)\,\cos(B)-\sin(A)\,\sin(B)$. There is no multiplication however?
Answer: Hint: $\varphi$ is such that $$\cos\varphi =\frac{C_1}{\sqrt{C_1^2+C_2^2}},\\\sin\varphi=\frac{C_2}{\sqrt{C_1^2+C_2^2}}$$
When $C_1,C_2$ are real, there is a real $\varphi.$
For complex $C_i,$ there is a complex $\varphi$ unless $C_1^2+C_2^2=0.$


Conservation of quantum information in mixed states quantum secret sharing (QSS) schemes?

Question: Consider a $((3,5))$ pure state quantum secret sharing (QSS) scheme. For instance this paper: arXiv:quant-ph/9901025. If I divide any 5 shares to two sets then allways one of those two set are athorized meaning they have full information about the encoded state. Now let me discard one share and design a $((3,4))$ QSS scheme. In that case I have a mixed state QSS scheme. In this case a set with two shares is unauthorized. So if I divide the set of shares into two set each with two shares, non of these set of shares have any information about the encoded state. So my question is in this case where is the information? Whats espcial about pure states that somehow conservation of quantum information works for them?
Answer: This is because of the no-hiding theorem. If a quantum channel completely erases information, then its complementary channel should preserve all the information that the input state has. Therefore for any pure QSS scheme, the complementary set of any unauthorized set must be an authorized set. The vice-versa follows from the no-cloning theorem. The reason this doesn't apply to mixed QSS scheme is that it is actually possible to hide quantum information in multipartite quantum entanglement, as one can see from the possibility of $((n,2n-1))-$threshold pure QSS scheme. For example, in your example of $((3,4))-$threshold mixed QSS scheme, the complementary set for any unauthorized set is not the whole environment surrounding that unauthorized set. So the information flow is not wholely headed to the complementary set of the size 2, but to the purification system of the unauthorized set, which has the size of 3.


Feature selection / missing values

Question: What are the top (including new, if any) algorithms to perform features selections without removing or altering the missing data points ? Thanks
Answer:
Random Forest: Random Forests are often used for feature selection in a data science workflow. This is because the tree-based strategies that random forests use, rank the features based on how well they improve the purity of the node.

Recursive Feature Elimination (RFE): RFE is a popular feature selection algorithm that recursively removes attributes and builds a model on those attributes that remain. It uses model accuracy to identify which attributes (and combinations of attributes) contribute the most to predict the target attribute.

Lasso Regression: Lasso Regression is a popular method to reduce overfitting in a model. It does this by making the coefficients of the features that do not contribute to the model output zero, effectively eliminating them.

Ridge Regression: Ridge Regression is a method that adds a degree of bias to the regression estimates, which reduces the standard errors. It might not eliminate the features like Lasso, but it will assign them lower weights.

Elastic Net: Elastic Net is a middle ground between Ridge Regression and Lasso. It penalizes the absolute and square size of the regression coefficients.

Boruta: Boruta is an all-relevant feature selection method. It tries to capture all the important, interesting features you might have in your dataset with respect to an outcome variable.

XGBoost: XGBoost provides a built-in feature importance plot which ranks the features based on their importance in the model.

LightGBM: LightGBM also provides a built-in feature importance plot which ranks the features based on their importance in the model.

Variance Threshold: This method removes features whose variance doesn't meet a certain threshold. It assumes that features with a higher variance may contain more useful information.

SelectKBest: This method selects features according to the k highest scores of a given scoring function.

Remember, these algorithms do not remove or alter missing data points, but they may be affected by them, so it's always a good idea to handle missing data appropriately before feature selection. Caution, if you want to make a model without touching NaN values and you want a model that can handle it directly then you can go with XGBoost, CatBoost
Comment: This is gold! Thanks a lot.
Comment: Happy to help you. You can close the question if you are satisfied

Feature selection / missing values


What happens if the sample size is too high in logistic regression?

Question: I know there's a minimum sample size calculation for logistic regression and I've found many discussions about it. However, what I'd like to know is what happens if the sample size is too high. Hypothetically, let's say for about 200 predictors, if I have 12,000 records, will there be any problems with the analysis? Should I check for something before I choose the data? I don't have actual proportion of the data but assuming 50% positive cases, will there be any problem with the assumptions and analysis?
Comment: Perhaps look at https://stats.stackexchange.com/q/2516/601
Comment: "I don't have actual proportion of the data but assuming 50% will there be any problem with the assumptions and analysis?" 50% of **what**?
Comment: I didn't know it mattered. I'd say "positive cases". The outcome could be `deceased` or `alive`.
Comment: @John, it was a good read. Thank you for sharing. I think I'm even more confused now. But that aside, the discussion seems to be for linear regression. Can this be generalized to logistic? After all, they're both linear. Am I correct? Although, what confuses me is that in linear regression we are looking for the difference in mean, for instance. What's the effect size in logistic regression? How would you explain it?
Answer: I would argue that with 200 predictors that 12,000 records is small, maybe too small.  Consider how many two factor models you have just assumed into existence.  Unless you have the sincere belief that all 200 factors are the true model in nature, just the pairwise combinations are 19,900.  You have vastly overrun your records.
If you cannot reduce that down to a reasonable model size using logic then you will have no ability to perform model selection to determine which of the models is a good model of nature.  Mechanically, of course, there is no strict objection to having a model of 200 factors, but if everything is highly correlated then you probably do not really have 12,000 independent observations.
I would look closely at the relationships among my 200 variables before I went any further.
EDIT
The phenomenon you are looking at is called the Jeffreys-Lindley paradox and it is a theorem that states that if you have data drawn from a normal distribution and a sharp null hypothesis such as $\mu=k$ then all true null hypotheses will be falsified if the sample size is large enough.  Note that this assumes that the computers have infinitely  many digits and you can purchase $\pi$ or $e$ ounces of wheat.
This led to the discussion of small departures from normality, which led to the discussion of other distributions.  There is a discussion out there that you can avoid this with a Bayesian solution.  You cannot.  This is an intrinsic problem with sharp null hypotheses.  Bayesian methods, because they operate in the parameter space rather than the sample space, cannot process sharp null hypotheses because if the data is truly normally distributed then $\Pr(\mu=k)=0$ since it is a single point on a continuum and has zero measure.  Bayes will not help you escape this problem if this is your true hypothesis and not one of convenience.
You will not face this problem, however, as you are already planning on taking a Bayesian way out.  If you chose step-wise regression the model selection criterion; the AIC, BIC, DIC or whatever; allow you to escape the paradox.
When you use information criterion you are using stylized Bayesian procedures that are point estimates of the posterior density over the model space.  If you have a variable that matters that is also very close to zero, this will be accounted for properly by the information criterion.
If you drop a variable, let us say $x_{153}$ from the regression, this is no different from setting $\beta_{153}=0,$ except that it bypasses the paradox entirely because Bayesian methods are not subject to the paradox because they operate in the parameter space.
So, the answer is that yes the paradox applies to logistic regression, but does not apply in your case.
Please pre-filter your predictors to strip out those that you believe are largely identical.  Two hundred predictors are a lot of predictors for 12,000 records if you have no idea what the true model may be.  This will be even more so if you believe that the 12000 are not truly independent as is often the case in life sciences and social sciences data.
I think you have the opposite problem.
Comment: I disagree with Dave. Many ML methods are perfectly suitable for this problem. Try out LASSO, logistic regression, or ridge regression for a start.
Comment: @OliverAngelil, I agree with you. The discussion came about when we started talking how to discuss regular logistic regression with other ML models like you suggested. I questioned whether its okay to compare logistic done in statistical method to other machine learning models. If we use large datasets, the ml will work fine, but will it still be true for the statistical model?
Comment: @DaveHarris, i think you also make a good point. Assuming, application of stepwise method for feature selection, the features were reduced to, say, 14. How would this affect then? Can we still confidently say the results obtained from the analysis is reasonable? What I understood about sample size is, large datasets may not always be good thing. It may find even a small differences in effect size and become significant in linear regression (?). I don't know how this translates to logistic regression.


All Subscribers issues across Multiple BU's

Question: I have a Master BU and 5 child BU's. When a subscriber signs up on the website they were added to child BU and a welcome Email is triggered, they were added to All subscribers in all child BU'S and Master BU's. If I unsubscribe from the mail child BU, they are still showing active in other Child BU's. Is there a way that we can set up that will be adding to that Child BU only not to all other BU's
I did check the trigger under subscriber management it is adding to the correct list and there are 2 check boxes "Add Subscriber to list" and "update Subscriber"
I did also check the Define Subscriber filter, there is one Filter as Reduced Frequency Is YES
Do I need to change anything here?
Answer: There is only one All Subscriber list that is shared across different BU's on your instance.
To keep the Unsubscription status processing at global level, meaning it will reflect the status the same between all the BU's, change the Unsubscribe Settings to be Subscribers will be unsubscribed from all business units in the Enterprise for every BU.
Keep in mind this change will not work retroactively for the subscribers that have already unsubscribed.
The other point, if you need to adjust and keep the visibility of subscribers between BU's private, you will need to enable Subscriber Filter based on a subscriber attribute. This means every individual subscriber will be visible on top-level BU and the sub-BU level where it matches the filter criteria.
The most common solution is to create a new subscriber attribute like Brand or MID and use values specific to that BU as filtering rule.
Comment: Thanks @Rain for the quick help, this solution helps me understand the Subscriber filter


Implementing a lexer identifying tokens after creating DFA

Question: I want to understand something about implementing a lexer, and I dont want to use scanner generators. From what I have read is that I identify the specification of the language with regular expressions each for different token. Then I should make a big regular expression ORing all of the token's expressions, right?! Then create NFA then DFA of this big regular expression, right?! If so then when a word get matched by the final DFA how will I know which token this word represents?!
Comment: once a word has been matched, you know where you started, and you know where you ended, right?
Answer: FSM-based Lexer
Writing a finite state machine (FSM) lexer by hand, you loop over the characters in your input and process that with two levels of switch statements:

the outer switch statement is switching on the state;
the inner switch statement is switching on the character that was read.

This is an implementation of a finite state machine to process the tokens. The downside to this is that it can get complex to maintain, especially if there are many states to process each token. The upside is that it is easier to refactor to take advantage of finite state machines (e.g. using transition tables instead of switch statements).
Transition tables are like the switch statements: the rows define the states, the columns define the data values and the cells define the next state to transition to (with something like -1 to signal to stop processing). With this approach, the end state can be used to determine the token type. Here, you will have a token_type tokens[N_STATES]; array that you can then do token = tokens[current_state] to get the token.
Non-FSM Lexer
The alternative approach is to switch on the first character and then read the rest of the characters in that token as part of that case statement. This can be easier to read and simpler to write.
You can also split the characters into different classes (e.g. numbers, letters, minus and less than) that you can define as a 256 item lookup table. This can simplify the case statements.
Regular Expressions
Using a big regular expression is problematic as you noted, as you cannot get the token type. An approach here is to have a list of regular expressions that match the token and associate that with the token type. For example, in python:
_tokens = [
    (re.compile('\\s+'), WhiteSpace),
    (re.compile('[a-zA-Z_][a-zA-Z0-9_]*'), Identifier),
    (re.compile('[0-9]+'), Integer),
]

You will need to order these correctly (e.g. placing keyword matching before identifiers).
Comment: @Doggynub If you want to use a DFA, you need to mark each accepting state with the token type. That's not quite the same as the textbook DFA, but it's not actually that difficult. In the original patterns, each accepting state was distinct, so there's no problem; in the closure construction when you combine two groups of states including two different accepting states, you just keep the one with the smaller number (assuming you numbered the patterns in order). During the scan, you also need to remember the last accepting state's position and token type, because you might need to fallback.
Comment: I think I am going to use the transition table, though I have a question abut keywords, In my DFA I dont have states for keywords so I am wondering if I finished in an identifier state should I check if it is a keyword by having all keywords in a table and then looping to find the variable in the table or create a regex that have all the keywords ORed, which shall be faster?
Answer: What you're describing here is implementing a generated scanner by hand. That's not how you do it. Just write a loop containing a large switch statement whose cases are the initial letters of each token type, and each case is a loop to consume the rest of the token and return its type. The whitespace case is identical except that it doesn't return. The case for identifiers also needs to lookup a keyword table.


Bluetooth Health Device Profile (HDP) Sink Implementation in BlueZ 4.99?

Question: I am new to Bluetooth programming, and I am trying to create a Linux application which interacts with a Heart Rate Monitor (HRM) over Bluetooth. This would ideally be accomplished through either BlueZ tools (sdptool, hcitool, hciconfig, etc.) or the C Programming Language.
I assume the program would resemble the following:

Scan nearby devices.
Browse SDP of each device, searching for an HDP HRM Source.
Perform some sort of connection command.
Read from stream/file passed by connection command.

Of course, being new, my assumptions about program flow could be incorrect themselves.
However, I am unable to find any capabilities regarding the Health Device Profile in the BlueZ tools. In attempting to make a C application, I can find preprocessor macros for numbers relating to an HDP implementation in the BlueZ header files, but no functionality beyond that.
Some useful links I've found:

HDP V10 Specifications (PDF)
BlueZ HDP Python Example

System Information:

Linux Kernel: 2.6.37
BlueZ Version: 4.99
D-Bus Version: 1.0

To be more specific about my questions, is it possible to create an HDP sink using BlueZ tools? If not, is it possible to do so in C. If not, what is the best way? And where can I go to find documentation for HDP connections and possible examples. Search engines have proved unhelpful so far, so I am hoping SO can provide some direction.
Thanks!
Comment: So what's wrong with the python example you linked to?
Answer: Try Antidote, it compiles for Linux and has a built-in sink example
(healthd).
http://oss.signove.com/index.php/Antidote:_IEEE_11073-20601_stack


Standard form of group von Neumann algebra

Question: For a group $G$ we may define its left regular representation on $\ell^2(G)$ via $\lambda(g)\delta_h=\delta(gh)$ where $(\delta_g)_{g\in G}$ is the canonical basis. Then $M(G)=\lambda(G)^{''}$ is the generated group von Neumann algebra. By $\tau(x)=\langle x\delta_e, \delta_e\rangle$ it is given a faithful, normal state on $M(G)$. W.r.t. $\tau$ we may build the GNS construction of $M(G)$, this is called the standard form. In lecture notes by Vaughan Jones from 2009 he states that the group von Neumann algebra is already in standard form. This is not clear to me. I see that both the construction of the group von Neumann algebra as well as the GNS construction use left regular representations, but the GNS Hilbert space is then the completion of $M(G)$ w.r.t. tracial norm $x\mapsto \|x\delta_e\|$. Is this already complete? Do we then identify $x$ with $x\delta_e$ (which is possible since $\delta_e$ is separating)? It would be nice if someone could clarify what is meant with this assertion.
Comment: $\lambda(g)\delta_h = \delta_{gh}$, I guess.
Comment: You are right, I have fixed it! Somehow I mixed it with $(\lambda(g)\delta_h)(k)=\delta_h(g^{-1}k)$, i.e. the discrete fourier transform definition...
Answer: I guess one way to see it is by showing directly that $\mathbb C G$ is dense not only in $\ell^2(G)$ but also in $L^2(M(G),\tau)$ and those two norms, $\|\cdot\|_2$ and $\|\cdot\|_{\tau}$, do coincide on $\mathbb C G$.
Another approach I would suggest is through the notion of von Neumann dimensions. Since $\delta_e\in \ell^2(G)$ is a cyclic and separating vector for $M(G)$, the von Neumann dimension $dim_{M(G)} \ell^2(G)=1$; on the other hand, $L^2(M(G),\tau)$ is in standard form and thus $dim_{M(G)} L^2(M(G),\tau)=1$. As $dim_{M(G)} L^2(M(G),\tau)=dim_{M(G)} \ell^2(G)$, they are unitarily equivalent $M$-modules and hence may be viewed as one space. For detailed discussions on von Neumann dimensions, see Vaughan Jones' planar algebras lecture notes.
Answer: The standard form of a von Neumann algebra $M$ is a representation $M\subset B(H)$ that has a conjugate linear isometric involution $J$ and and a self-dual cone $P\subset H$ with

$JMJ=M'$
$J\xi=\xi$ for all $\xi\in P$
$aJaJ\subset P$ for all $a\in M$
$JcJ=c^*$ for all $c\in\mathcal Z(M)$

It is the "correct" representation to do Tomita-Takesaki theory. A sufficient condition to have such a representation is that $M$ has a cyclic and separating vector $\Omega$; in the case of the left regular representation of $G$, the additional property of having the trace allows one to define $J$ by
$$
Ja\Omega=a^*\Omega,
$$
and $P=\overline{\{a\Omega:\ a\geq0\}}$.
Comment: Thanks for your answer, I didn't know this definition yet, only the one I have introduced above (but I just realized that mine was (probably only?) for finite factors ...) Is it obvious to call it "the" standard form? As I have introduced it above, it was clear to me, since the trace is unique and GNS representation is up to unitary equivalence. In the case of group algebras, do we actually need the tracial property? Since we already know that $\delta_e$ is cyclic and separating?


Is it possible to receive copy of deleted facebook messenger messages under GDPR?

Question: Is it possible to receive copy of deleted private facebook messenger messages under GDPR if two recipients deleted them?
Comment: This question is a little unclear because it provides very little detail. Who sent the msgs, and who wants a copy under the GDPR? Is anyone in the EU or the UK? It could also use a little editing.
Answer: If Facebook still has a copy of your deleted messages, and if Facebook is able to tell that these messages are your messages, then Facebook should produce a copy of these messages in response to a data subject access request (DSAR).
But the important words are "if" and "should".
From the outside, it is not possible to tell how Facebook manages deleted messages. When both users delete a message, is this a soft-delete that merely hides a message, or does Facebook actually delete their message from the servers? If the message is actually deleted (which would be a GDPR-compliant approach), then it obviously cannot be produced in response to a DSAR.
The next problem is that Facebook is not known for being a particularly helpful data controller, and often makes it difficult for users to actually exercise their GDPR rights. So even if these messages still exist, it is possible that Facebook would be (illegally) withholding them in a DSAR response. In 2019, Ruben Verborgh chronicled his efforts to exercise a DSAR that goes beyond the incomplete "download my data" tool. It doesn't seem like he ever got the data he sought.
Answer: Just because the two people in the messenger deleted the messages doesn't mean that Facebook deleted them. It just means that the two people in the messenger (assuming there were only two) deleted them. At times when Facebook malfunctions, deleted messages reappear for a short time. This means that FB has them. So it's possible to get pretty much everything we've ever sent via messenger, you just need to convince them to give it to you. May need some kind of warrant or subpoena.
Comment: The question explicitly asked about GDPR, which requires neither a warrant nor a subpoena for an information request.
Comment: Your answer could be improved with additional supporting information. Please [edit] to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers [in the help center](/help/how-to-answer).


What is the most accurate way to get the data path for a value?

Question: what is the most accurate way to get the full path for a value so I can use it in a single property drivers.
Answer: I prefer to use the outliner to find the data paths of variables. If you set the outliner type to 'Datablocks' you can see the whole RNA structure of the current Blender file. If you hover with your mouse over a property Blender will show you how you can access it using the python API:
Comment: The location you get is a Python object of type Vector. You can access its x-value by adding `.x` to the data path. For the default cube this would be `bpy.data.objects["Cube"].location.x`. Alternatively you can access the vector components by index. `...location[0]` also gives you the x value. The index of the y value is 1 and the index of the z value is 2 respectively.
Comment: If I want to get the path for the x location for an object,I go to the data block and then objects and then my object and then location and then the x location but I couldn't get it right he give me "location only with out the x axis.how can I get that.


Disable profile field when module that created it is disabled?

Question: I have created a module that adds a field to the user profile. When I disable the module, I want the field to no longer be shown on the user profile. I do not want to wipe it out completely, since I do that on uninstall. I want it to come back with the original data when the module is reenabled I just want to have it not display when the module is disabled. Is there a way to do this? I am using Drupal 7 and the field is a text field and it is set to the default formatter when I create the instance. Is there a setting I can set the instance to in hook_uninstall that will hide it?
Answer: I managed to accomplish it through code by setting the field instance:
<code>    'display'       => array
      'default'     => array(
        'label'     => 'above',
        'type'      => 'hidden',
        'weight'    => '1',
        'settings'  => array(),
      ),
    ),
</code>
Answer: You would probably need to do something with your theme in order to hide the filed. Obviously you can't use your module, as it is disabled. You could do a check with module_exists to see if the module is installed, and if it is, print the info, if not, ignore it.


What is a quality SMTP server that can be downloaded for under $25?

Question: I am looking for a SMTP server that we can use for outgoing mail that permits a high volume (1,000+ per hour) without getting blocked. It could be downloaded on our machine or run online, but cannot cost over $25. Isn't there a good open source solution? I haven't been able to find one yet. Thanks.
Comment: Belongs on http://serverfault.com ?
Answer: Well, there are even free SMTP servers that can send a high volume of e-mail.
The problem is not in sending them, the problem is in delivering. You see, SMTP is a best-effort store-and-forward protocol - the e-mails are passed from one SMTP server to another in hope that it gets closer to the adressee's mail server (and usually it works). However, this also means that your message can be rejected or dropped anywhere in this chain of servers - or by the recipient. Once the e-mail leaves your network, there's not much you can do about it. In other words, it's not your server blocking the e-mails, but the servers it will be passing the mails to.
This question may be a useful reference for your problem; see also this article for some tips that will help your e-mail get delivered.
Answer: For that ammount of email, probably any server will do just fine. The problem is not to be blacklisted as a spammer. Jeff Atwood has a good blog post on the subject.
I personnaly would recommend Postfix or qmail, but that just me ...
Comment: great blog link, though the other answer has it, too?


How to handle bottle necks in agile testing procedures

Question: We have a problem in our development team, the development throughput is much higher than our QA members can test.
Our test team found itself in a situation where a new feature needs to be tested every two days.
So we have to do function, regression, exploration, and other testing, this loop takes a lot of time because any change or commit in the source code forces it to repeat everything.
They are now waiting for the developer to run his tests in the middle and before the end of the sprint. Is there some kind of best practice for such bottlenecks in the agile environment?

So one should rather solve the problem from the Project Owner side.
Plan fewer tasks in sprint planning?
Should tasks be rejected in order to avoid this bottleneck?
Should sprint planning be further punished?

I already described the problem in the retro, the solution was a shortened sprint planning. But, depending on the effort, we still have the problem that we run into this bottleneck over and over again.
But the problem is, we also write and review the test automation. But we simply can't keep up with passing the "normal" test, adapting the automatic test at the same time or creating a new one, everything together is simply no longer achievable.

So should the execution of the test automation also be included in
the sprint planning?
But wouldn't this even worsen the problem?
Where exactly are the priorities to be defined now? Write and adapt
the test automation, or just normal test, i.e. Explorative,
Functional.
What is important Whitebox or Blackbox test?

Especially small teams with few testers and a lot of tasks have these problems in front of them. On the one hand we all know that in the agile world speed is everything, but it is forgotten that the QA is sometimes simply too much burdened. We are only human beings!
Even if the project owner is looking for solutions and everything was reported in the retro, not everything can be solved. Depending on the size of the project, you always have a bottleneck somewhere, and yes it is somehow desperate!
Comment: @VishalAggarwal - this question only looks like multiple questions in one. The core question is "How do I deal with testing bottlenecks in an agile environment?". Everything else is part of that question.
Comment: How about starting by breaking this up in multiple independent questions?
Answer: I found myself in that very same position last year. With a team of around 12 devs and only 2 QAs we used up all our time testing features and couldn't do the (IMHO) more important work of improving processes, making our test infrastructure better and also carrying out some more long term initiatives that would improve things from a quality standpoint. Plus on a more selfish side it was a pretty lousy career wise as we couldn't do other stuff.
What I did was take the discussion with my manager, I explained the problem and how serious it was then tried to come up with a roadmap to fix it. With my manager's approval I got the entire team together and started working on the whole "shift-left testing" approach.

First the two of us trained every developer on how to read our
reporting tools, how to run tests and what to look for when a test
fails (to detect flakyness, automation bug or actual defect).
Then I created pipelines and scripts to make running tests as simple
for the as possible. We event went as far as trying to link
everything with Slack so a regression could be triggered from
chat... but had to drop this due to other limitations with our
Jenkins connection.
Developers would be in charge of testing their features. At first
they would send us PRs for unit/int/e2e test cases so we could check
they were covering all important scenarios.
Alongside that we kept working on our frameworks and code to make
everything as easily to expand and understand as possible.

After about 6ish months of that the team does task estimation by taking testing into account and they are comfortable enough with our frameworks that everyone can review QA/test PRs so I'm not even the bottleneck in that (the other guy left so, I'm the only QA).
The best part is that I hardly ever write tests anymore... I write the infrastructure and frameworks we need and keep pushing for CI/CD and only get down to writing tests when some huge feature comes along.
Your milage will certainly vary and I was really lucky to have a team that wants to take ownership of every aspect of the features they make so they were pretty onboard with the transition but that is how I handled that very common scenario.
Answer: The whole team is responsible for quality. Test work-items are activities in a Sprint not a phase, everyone in the team can and should pickup test activities. Testers bring QA knowledge to the team, share it instead of doing all the work. Break the handover pattern.
Yes test automation should be executed during the Sprint, the product should be potential shippable. Meaning PBIs (Product Backlog Items) should be DoneDone.

Our test team found itself in a situation where a new feature needs to
  be tested every two days.

Automate everything. Performing Agile teams practise "XP" and start with the Test First practise. Working with short cycles means you need to change the way you work. Traditional by hand testing doesnt fit these short cycles. Short exploratory sessions (to check the test automation didnt miss anything) do.
I would suggest that you and your Team (and or facilitated by an Agile coach/Scrum Master) go over "A Coach's Guide to Agile Testing".
Answer: The answer is simple!
1- Work ahead. Yes, working ahead will create balanced deployed work ready for testing throwout the sprint cycle, and will give developers time to respond to testing feedback early away from sprint review.
2- To achieve #1 above, implement the PROPER agile rule of under-estimating and taking on work per developer that can be done and tested within a sprint span, leaving proportionate room for testing in sprint days.
Here is a full article I wrote about my own experience with the topic:
I solved Agile testing bottleneck problem!
https://medium.com/@salibsamer/i-solved-scrum-sprint-end-testing-bottleneck-problem-bfd6222284a1


Populating a tool's field in Qgis Graphic Modeler

Question: I am trying to pouplate a tool's X and Y coordinates from a point file and I want to do this in the graphic modeler.
-But how do i connect the coordinates with the appropriate field in the Target X and Y coordinates of the tool, in this case when calculating the Upslope Area with a SAGA tool?
Answer: the TargetX and TargetY input of the slope algorithm are single values of you need to take these inputs from the vector layer?
If they are single numeric values you can add X and Y as numbers in the modeler and then link the values of the algorithm to them.
From the input parameters you can drag and drop the number parameter and give it default values.

Then you can link the values to the alorithm

Is that what you are looking for?
Comment: Yes @matteo, I have a vector layer containing several points where attributes for x and y is stored. I need to somehow iterate these points, take out the numbers for x and y and then run it through the Upslope Area tool. So, this actually includes a process of iteration, but do you have an idea of how to do this? And how did you manage to connect X and Y in your screendump?
Comment: @Andreas.. mmm you can do a batch job with processing.. however the input parameter of the saga algorithm are taken as single values not as vector field.. I think that you need to use python to do the magic..
Comment: Yeah, i was approaching the same conclusion of using python. You are absolutely right that the algorithm doesn't use vector field values and this is the obstacle. I'll try and circumvent it with scripting and will post the solution here if I somehow manage to finish it.


How to change the tabbar color in vaadin?

Question: Hi want to change the tab color when the tab get focus in vaadin?can any one help me how to customize tabsheet to achive this..
Answer: It's a good idea to use a tool like firebug to inspect the DOM structure of the components. For example, when inspecting the DOM structure of the TabSheet example in the Sample, you will see that all tab has the style class v-tabsheet-tabitem. If you select the first tab, it will get the following style class "v-tabsheet-tabitemcell", "v-tabsheet-tabitemcell-first" and "v-tabsheet-tabitemcell-selected-first". If you select the second tab, it will get the following style classes: "v-tabsheet-tabitemcell" and "v-tabsheet-tabitemcell-selected". As you will see, the styles you need to modify are a bit dependent on the tab's position in the tabsheet.
About changing the color of the tab, let's take a look at the selected tab's css.

<code>
.v-tabsheet-tabitemcell-selected {
   background-image:url(common/img/vertical-sprites.png);
   background-position:left -1444px;
}
</code>

As you can see, the actual css is not complicated. The technique used in the css is however a not so common, it uses a sort of optimization. All the background images are joined in one single png image and the background image's position is adjusted so that we get the image we want to show as the background. What you need to do, is to create your own theme and modify that image to suite your own needs. Check the Book of Vaadin for more details about creating custom themes.
Answer: Actually, you do not need to know the technique (CSS sprites) in order to change the background of the tabs. You will only need to use regular CSS, no magic involved.
So create a new background image (of a solid color is not enough) and set that to the background of the relevant element. Repeat for all relevant elements that are contained in the tab (they might also specify some background).
If you wish to modify the original images from the Vaadin Reindeer theme, they can be found from here: http://dev.vaadin.com/browser/versions/6.4/WebContent/VAADIN/themes/reindeer/tabsheet/img


Which word describes this concept?

Question: Someone is having a bad (or good) day, and from the events that happened to him/her, this person thinks that the universe is against (or very good with) him/her. Then, an event happens that is so good (or bad) that it seems to make this day suddenly seem to become the opposite of what it was. It could be anything like winning the lottery, his/her crush deciding to date him/her, this same crush rejecting him/her when it seemed that such a thing wouldn't ever happen, or a relative dying. What word defines this event that seems contrary to how the day initially seemed to be? I'd like the word to be an adjective but if it can't be an adjective then I guess I'll need to accept another type of word besides adjectives. The word needs to be used to say things like "What a(n) [...] event" or "This event really is/would be [...]". Thank you in advance.
Comment: I hope it'll now make better sense that I edited that part to clarify it. The word needs to be used to say things like "What a(n)  event" or "This event really is ".
Comment: It's the [*vagaries*](https://www.dictionary.com/browse/vagaries) — the unpredictable ups and downs — of life.
Comment: From the SWR tag: "This tag is for questions seeking a single word that fits a meaning. To ensure that your question is not closed as off-topic, please be specific about the intended use of the word.  INCLUDE A SAMPLE SENTENCE demonstrating how the word would be used."
Comment: What should the adjective be modifying? "What word is defined as this event..." makes it seem like a job for a noun.
Comment: You should add your sample sentences to the question since comments can be removed.
Answer: vicissitudes neatly sums it up.

a favorable or unfavorable event or situation that occurs by chance : a fluctuation of state or condition

the vicissitudes of daily life
[Merriam-Webster]
Comment: This word is quite close to what I want to say though it'd be better if the word's definition stated that the event or situation the word describes is so favorable (or unfavorable) that it changes a particular time period from good/bad to bad/good. If such a word doesn't exist then you can also say that the word I'm looking for doesn't exist.
Answer: A day with so many reversals of fortune might be called a day worthy of the Fates.
Wikipedia: https://en.m.wikipedia.org/wiki/Fates
The concept that you want to convey is very complicated. This means that the adjective or phrase you want will almost certainly have to be drawn from literature or mythological concepts that are widely known.
You can make up an adjective related to a character in a more contemporary work, but here you have to know your audience. Even the most widely-watched TV shows have not been seen by everyone. Nor have most video games.
Answer: How about reversal?
From https://www.merriam-webster.com/dictionary/reversal

3: a change (as of fortune) often for the worse
Comment: The word looks good but seems like it needs more words after it or before it in order to convey the meaning I want (except if it can convey it alone, I don't know that, if it does you can tell me).
Answer: You could use game changer

a newly introduced element or factor that changes an existing situation or activity in a significant way.

This can be used to describe the event that changed how the day unfolded.

I woke up feeling miserable, but winning the lottery was a real game changer.

Which word describes this concept?


Selecting Sheets to copy to a new worksheet based on Cell values

Question: I have Sheets renamed as "1","2","3",...,"31". I need a code to select the renamed sheets based on an interval value that would be provided on two cells on a sheet named "Email Summary". so for example, cell L13's value is 1 and M13's value is 5, the code would copy the sheets named "1","2",...,"5" to a new workbook. if cells L13 and M13's values are 8 and 15 respectively, the code would copy the sheets named "8","9",...,"15" to a new workbook.
Comment: Hi, welcome to stack overflow. Please refer the
[ask] link for more details on how to ask a question and update your question accordingly. Show us what you have tried.
Answer: You could try this for starters.  I've edited it a bit to a) make it actually work :), and b) because the sheet names as numbers gave VB some issues.
<code>Sub copy_stuff()
Dim intshName As Long, thatbook As Workbook, strshName As String
Set thatbook = Workbooks.Add
   On Error Resume Next

   For intshName = ThisWorkbook.Sheets("Email Summary").Range("L13").Value _
      To ThisWorkbook.Sheets("Email Summary").Range("L15").Value
        strshName = Trim(Str(intshName))
        ThisWorkbook.Sheets(strshName).Copy after:=thatbook.Sheets(1)
    Next intshName
    On Error GoTo 0
End Sub
</code>
Comment: @Horthgar I'm getting an error with the code. "Compile error: Invalid outside procedure
Comment: @Horthgar It works! I just need to replace the .Copy after to .Copy before. Other than that, it's perfect. You're amazing.


How to create workflow for sending mail for incomplete tasks

Question: I have created one task list.In that list Status,Assigned To, Task column is there.one month time period will be given for every task from created date.If the status column is not changed as completed  within one month , the assigned to person should get the mail with the task name and "your task is not completed".
How to create workflow for that using sharepoint designer.I am using sharepoint designer 2010,sharepoint 2016 onpremise.
Answer: You could use the following workflow:

1.First we need to add a variable (end date):

2.Then set the variable value as Start date +30 days, when Today=end date and the status is not equal to "Completed",  it will send mail to people assigned to. (Add a step: send a mail, then select people > Workflow lookup for a user > set the value in pop-up window as the screenshot shows:

3.As to the email content, you could use "[%Current Item:Task Name%]has not been completed." as it is shown in the screenshot.
4.At last, set the workflow settings as start workflow automatically when an item is created.
Comment: The reason why you have not received the mail is that the workflow lacks a loop. It will only run once when an item is created, if it does not satisfy the condition, it will not send the mail. It is recommended that you use workflow 2013 to add a loop to this workflow, here is a similar case for you to refer to: https://docs.microsoft.com/en-us/answers/questions/847604/sharepoint-designer-2013-loop-1.html?childToView=863805#comment-863805
Answer: For testing purpose i gave add 1 day to current item:start Date(output to Variable:end date).In Assigned to i gave my name.All the Above mentioned steps i have done.But i did not get any mail.
Anything i have to do in my task list?
Did i missed anything?


Python 3 - How to input data without pressing  in OSX

Question: I am attempting to move a character using the "asdw" keys in a game, but I cannot find a way to constantly input data without pressing return. I have seen that on windows there is a module called msvcrt, which has a getch function, so I am wondering if there is a way to simulate this in OSX, or more simply to just constantly input data from the keyboard.
Comment: Duplicate of [raw_input in python without pressing enter](http://stackoverflow.com/questions/3523174/raw-input-in-python-without-pressing-enter)
Comment: No, it isn't. The accepted answer to that question is blocking, i.e. it will *wait* for a key press. If he used that solution in his game, everything on the screen would freeze while it waited for the user to press a key.
Comment: It is more likely a duplicate of this: [Polling the keyboard in Python](http://stackoverflow.com/questions/292095/polling-the-keyboard-in-python). I can't reflag the question, unfortunately.
Answer: Try the curses library:

http://docs.python.org/py3k/library/curses.html

Curses is a library for controlling the terminal, and includes features such as drawing box shapes as well. It's available on any POSIX-compatible system, which includes Mac OS X and GNU/Linux.
Here's an example:
import curses
import time

# Turn off line buffering
curses.cbreak()

# Initialize the terminal
win = curses.initscr()

# Make getch() non-blocking
win.nodelay(True)

while True:
    key = win.getch()
    if key != -1:
        print('Pressed key', key)
    time.sleep(0.01)

Comment: Out of curiosity, what graphics library are you using? If you're using something that's designed for writing games, it should have some kind of keyboard system built in. By the way, if you want graphics and interactivity, pygame (http://pygame.org/) is great.
Comment: It is a graphics library that we used in my class at school. It's not very good for using this game, so I should look into using pygame. Here's a link the the module though. http://mcsp.wartburg.edu/zelle/python/graphics/graphics/index.html
Answer: You can use Turtle to do something like this:
import turtle
Sc = turtle.Screen()
Sc.setup(width=0, height=0)         #this hides turtle's windows
def a():                            #that's the function that you want to run when the key is pressed
    #code here
    Sc.listen()                         #this tells the program to listen
    for a keypress
    Sc.onkey("#The key here", #the function call here) #this tells the program

What function to call when a certain key is pressed
# An example of pressing the key "w"
Sc.onkey("w", a)

Comment: Please learn to format your questions, specifically code. You can use triple backticks or an indented block to format code. There are also handy helper buttons :)
Comment: I'm sorry if the comment is somewhat messed up, but it's the first time that I actually write something on stackoverflow


Is there a way to automate perl script in call-back style on linux platform?

Question: I have a perl script that does polling a file's existence in every 600 seconds before it goes on to finish its task.  I am using crontab to schedule my script.  I wonder is there an event system on linux that I could register my perl script so that system does the call-back if the file exists?
Answer: Check out http://search.cpan.org/~mlehmann/Linux-Inotify2-1.2/Inotify2.pm (Linux::Inotify2 - scalable directory/file change notification).
Also check out incron
<code>It consists of a daemon and a table manipulator. You can use it a similar way as the
regular cron. The difference is that the inotify cron handles filesystem events rather
than time periods.
</code>
Answer: Inotify should be your friend for this one... . There seem to be perl bindings as well. Your kernel needs to support this though... .


How to attach a site thumbnail from user submitted links in a facebook application

Question: The Facebook application I had in mind has users submit links from sites. I would like there to be a thumbnail of the site, similar to what happens when you post/message someone a link and a thumbnail automatically shows up. Any thoughts on how to go about doing this?
Answer: The sites you link to need to have Open Graph tags (https://developers.facebook.com/docs/opengraph/) on their pages to set the default image, description and title for this to happen. If those meta tags are not set, the first image on the page will be the default along with other generic information Facebook is able to scrape from the page.
If you want to test out a few pages and see what information they have set, use Facebook's URL lint tool (https://developers.facebook.com/tools/debug). Simply copy and paste any URL in there.


Is a K-1 fiancé(e) visa required to enter United States?

Question: I'm reading about the K-1 fiancé(e) visa available to foreign nationals planning to marry a US citizen within the US, and am wondering if its required for someone who has other legal means of entering the US?  Specifically, for an EU citizen who can enter the US under the VWP, should a K-1 application still be done?  Or is the K-1 simply for those who have no other legal means to enter the country?
Answer: The answer is No, it is not required. However, in most cases there is no other legal way for an alien fiancé who is not a permanent resident to enter the U.S. for the purpose of staying in the U.S. permanently. (I am assuming the question is about fiancés who intend to immigrate to the U.S., because that's what K-1 is for. If one only intends to get married during a brief trip to the U.S. and then leave, then VWP or B-2 visa is appropriate.)
The fiancé is not eligible for an immigrant visa, because he/she is not married yet and thus not yet a relative. And most categories of non-immigrant visa (and VWP) require the holder to not have preconceived intent to immigrate using that visa (i.e. not intend to stay and apply for Adjustment of Status during that entry) both when applying for the visa and when using it to enter the U.S. This includes categories like B visas (tourist or business visa), F visas (student visa), and most other types. So these visas cannot be used when one intends to stay. (One could intend not to stay when entering, and change their mind later, but since you're asking this question at this stage, I'm assuming you have a preconceived intent to stay.)
There are a few types of non-immigrant visa that don't have this requirement of not intending to use it to immigrate. This includes the K (fiancé) visa itself, as well as H and L work visas. So if you are a fiancé and, for example, are working on an H or L work visa, then yes, you can feel free to use that to enter the U.S. for the purpose of getting married and applying to immigrate, without getting a fiancé visa. But in all other cases, you will have to get a fiancé visa (or marry outside the U.S.).
Comment: What about https://www.uscis.gov/sites/default/files/files/nativedocuments/2013-1114_AOS_VWP_Entrants_PM_Effective.pdf? Does that apply only if the marriage occurred outside the US?
Comment: @phoog: I am not sure what you mean by "what about". They are two separate things. Someone obtaining a nonimmigrant visa or entering the US as a nonimmigrant must show that they do not have *preconceived intent* to immigrate using that nonimmigrant visa or status. The consular officer (when applying for a visa) or the immigration officer (at entry) is responsible for determining whether you meet that at the time of getting a visa or entry and denying you if not. However, for a nonimmigrant who has already legally entered the US, they are eligible for Adjustment of Status according to the law.
Answer: The answer is depends.
I would suggest that you consult the immigration lawyer before attempting anything other then the K-1 route if you intend to get married.
As was explained to me by a lawyer awhile back if the entry of a foreigner you have married under a B1/B2 or VWP is suspected to be for the purpose other then tourism you could have problem with CIS during the adjustment of status process.
Having said that, I am aware of multiple cases where a person had entered the United States under the B1/B2, got married several months after that entry and received Permanent Residency in the United States through adjustment of status, so yes using VWP may be possible but again consult a lawyer.
Answer: My husband was in the US for two years before we met on an over-stayed H2B visa. After we met and dated, we lived together on and off for about 10 years and finally decided to get married.
He was able to get an adjustment of status no problems. But...his H2B allowed him to work for three months when he first came here and get a social security card (only one that allowed him to work with a work permit) and a driver license. He was able to work with that Social Security Number and he paid taxes on everything he earned for the entire time he worked, even though he had over-stayed. We had to have a lot of proof for our interview after marriage. Tons. So, I'm not recommending anything here, just saying, it was better that we had a long term relationship before we went to our interview.


Is there any alternative theory that gets rid of gravitational waves, yet fits all data?

Question: Is there any theory that gets rid of gravitational wave and still matches with all correct predictions made by standard physics theories? (e.g. General Relativity)
Comment: (Advanced) LIGO has, on 11 February 2016, announced detection of gravitational waves from a binary black hole merger with more than 5σ
certainty, so this question now seems to be asking for the impossible.
Answer: This is not possible at long distances because of special relativity. If gravity is a long-range force, the effects must be transmitted at the speed of light, so that there must be gravitational waves. The reason is that if you shake a mass at one point, the different position of the mass must lead other masses far away to shake later, at the speed of light. The outward propagating pulse that tells the masses where the mass is is the gravitational wave.
Further, there is experimental data on binary pulsars that show the energy carried off by gravitational waves. While we don't have direct evidence that this is what is going on, the pulsar decay period is consistent with the predictions of General Relativity regarding the waves.
Comment: +1 Gravitational Waves And Propigating Fields of force are governed by specific observable laws.
Comment: Great to hear you say this Ron - if one believes in universal causality, and if one accepts STR, then you know there have to be gravitational waves even before you fire one neuron thinking about any theory of gravity - there's no other way out. People make a great deal about Einstein's theory foretelling gravitational waves but they've got things around the wrong way: the the theory had to be built to produce them from the outset, as Einstein clearly knew.
Answer: I heard about no such theory. If space itself is a dynamic structure, which means it could change, then wave may be a necessary part of such theory
Answer: QED theory gets rid of gravitational waves and still matches LIGO senstivity response from 35 to 250 Hz. QED here is a simple form of light-matter interaction proposed by Feynman and others. QED theory is based on Planck's law that negates the heat capacity of the atom under high EM confinement which occurs as NPs of cosmic dust in the debris of the black holes absorb heat in their surface because of their high surface-to-volume ratios. NPs stand for nanoparticles. Hence, conservation proceeds as the NPs emit light rather than increasing in temperature. See:
https://www.prlog.org/12543050-ligo-sensitivity-and-cosmic-dust.html
Similarly, all heat transfer at the nanoscale may be explained by QED theory. See:http://www.nanoqed.org, 2010-2016.


How to display an RSS feed as a widget (or "badge") using PHP?

Question: I have an RSS feed from a wp blog (link), tunneled through feedburner, that I would like to display as a widget in another website.
The widget display can contain simply the headers taken from the feed, and the link to their respective posts.  I understand that there are many available web services for creating something like this (a few examples: 1, 2, 3)
But they all include a link to themselves, which I would like to save from the widget.
Instead, I would much rather have some php code on my server that will create this widget, so it could later be embedded into the other site like this:
What php code can perform this?  (I have seen a similar question which was asked two years ago, but the answers didn't include any examples)
Thanks.
Answer: you can use the widgets from http://www.rssfeedwidget.com/ to display your rss feed.


Can I install Windows on a diskless system with iSCSI?

Question: I'm reorganizing my home network, which now includes a NAS box, that, among other things, allows me to export partitions via iSCSI. Now I'd like to get rid of the harddisk in my Windows machine, as it makes quite an amount of noise and provides no redundancy, so I'd like to boot from the network and have my system installation on iSCSI.
As the NAS box runs Linux and this is just enough of a personal itch to scratch, I'm willing to code my way around some problems. I understand the Windows boot sequence is very much like Linux's in that a kernel and an initial set of drivers is loaded as blobs by the bootloader, then the kernel is invoked, which then initializes and loads the drivers from the image left by the bootloader, however the devil is in the details in this case.
My approach would be to provide an iSCSI initiator as an EFI Boot Service, which should allow the loader to retrieve the kernel and drivers, however I see issues with the initial installation (network drivers are loaded after SCSI drivers in the installer), and whether network drivers can be part of the dependency chain for Boot drivers.
Is it possible to load network drivers that early in the boot process, and if yes, can I somehow influence the preparation of the Boot driver collection image so that they are included? Can I get around the installer limitation?
Answer: No need to reflash your firmware or pay for a software solution, especially if you need to boot only one computer.
The solution is:
gPXE + iSCSI initiator plus some cooking.
Most of what you need to do is explained here:
http://www.etherboot.org/wiki/sanboot
This works for Windows XP to 7 and for Server OSes too.
Answer: You can reflash your NIC's firmware with iPXE, which will allow you to boot directly from your iSCSI target.
I prefer to use the chainloading method as I'm not sure if VMware ESXi will play nicely with the NICs reflashed and the dual-NICs I have are too expensive to mess around with.
Answer: Windows Server OSes 2003 and newer allow for iSCSI Boot from Microsoft.  TechNet Article
CCBoot apparently allows one to also boot client OSes XP & up, but it's not free.  I also just found it via Google, so I have no idea if the product works, how well it works, or if the company is any good.  It does appear that the server needs to run Windows as well as the boot client.
Answer: Basically anything newer than XP will allow you to install directly to iSCSI without modification, but be aware:  the recovery partitions do NOT support iSCSI.  This is a problem with Windows 10, which regularly wants to boot the recovery partition when doing major system upgrades.  To do those, you'll have to copy the image to a local disk, apply the update, then copy it back, attach to the iSCSI device with a different machine capable of editing the registry, disable one of the secret firewall rules that prevents iSCSI from working via regedit, and then you should be able to boot it again.
I'm not sure how this got through QA since iSCSI booting is supposed to be an officially supported feature, but despite all the people asking about it, I have yet to find a solution that works.


MAX2769 I & Q For Signal Acquisition & Tracking

Question: Having pulled data from a MAX2769B in device state 2 (2-bit I only), I have found satellite signals by multiplying the I-only data by the respective PRN and taking the FFT of the data. Using this approach, I set the imaginary part to zero, and fill in the I*PRN data for the real part, thus real only data. If I configure the device to produce the quadrature data and attempt the same procedure, it's unclear what I should do. My first pass attempt at the approach did not produce a correlation peak at any frequency. If I scrap the Q data and fill it in with zeros, I get the same answer as before, and all is well. Should the quadrature data be used in an acquisition? Does it help? Presumably, it should be used in tracking, but then I would ask a follow-up question as to whether the quadrature data should be multiplied by the PRN sequence.
Answer: Yes both I and Q (in-phase and quadrature) data should be used in acquisition, even if the signals themselves are real (for example BPSK such as with GPS). The primary reason for this is an inevitable frequency offset due to Doppler from the relative motion of the SV and ground receiver, as well as small offsets in the master clocks themselves in both devices.
When using both I and Q to correlate to a real sequence with a frequency offset, the correlation peaks themselves will rotate at a rate that is equal to the frequency offset (either positive or negative rotation depending on if the actual carrier frequency is higher or lower). With this, we can measure the rate of rotation during acquisition and use that to correct for carrier offset (carrier recovery).   The correlation peak will also reduce depending on the frequency offset and total time duration in the correlation as I further detail at this post.
If the frequency offset is greater than about $1/(2T)$ where $T$ is the total correlation time, then the estimated frequency offset would typically be stepped by that amount ($1/(2T)$) between correlations combined with a threshold detector for a correlation peak to indicate the frequency is close enough for fine acquisition which can then proceed using the I Q correlation peak values as explained further here, or alternatively multiple correlators can be run in parallel when resources allow and a fast acquisition is required (Essentially what I am doing here using FFT's for fast processing to simultaneously acquire in "one-shot" the carrier offset and code offset). Reducing $T$ is also an option, but that will also reduce overall signal to noise ratio.
Another technique for acquisition is to down-convert to baseband using a slow frequency ramp (which is similar to step in frequency and correlate with very small and very frequent frequency steps). Below shows an example result with an actual GPS signal using a frequency ramp that sweeps from -5KHz to +5KHz over a time duration of 50 ms. (Since the GPS C/A code repeats every 1 ms, the frequency change over any correlation interval is 10KHz/50 = 200 Hz which is less than the maximum $1/(2T)=500$ Hz interval that I recommend above.  We can see here at the 200 Hz / correlation interval ramp rate the correlation peak is sampled with approximately 7 visible peaks.

The number of samples that is visible would reduce as the ramp rate increases. At a 500 Hz rate, we would still be ensured 3 samples and therefore one close to the peak for a successful acquisition. I demonstrate this in the plot below with the same 50 ms data capture by extending the frequency ramp to go from -12.5KHz to +12.5KHz or 500 Hz per 1 ms correlation interval (of course what we would actually do is ramp over a shorter capture using the maximum possible frequency offset range we expect given Doppler and other frequency offset sources, for GPS +/-5KHz is a reasonable range for most applications):

Specific to the OP's question, the above correlation results shown are the absolute magnitude using I and Q ($\sqrt{I^2 + Q^2}$). Below shows the complex correlation result for the same last plot above plotted on the complex I and Q plane. The maximum correlation in this result ended up around 20° but could have arbitrarily been anywhere which is why we need to use both I and Q at this point in the processing.


ASP.NET and Timers

Question: Consider this code...
<code>using System.Threading;
//...
Timer someWork = new Timer(
    delegate(object state) {
        //Do some work here...
    },
    null, 0, 60000);

HttpContext.Current.Application["SomeWorkItem"] = someWork;
</code>
Could this be dangerous? Caching a timer in the Application to perform some work in the background while your site runs seems safe, but I wondered if anyone has some experience with this.
I'm sure that writing a Service to run in the background would certainly be much better, but sometimes that isn't always an option. Is this an alternative?
Answer: The problem with this is that you are not guaranteed the process still being alive. IIS will reclaim the process basically whenever it feels like it, so you run the risk of it not being performed.
If you need this work done then you need to either code it into a web call, or have a service running in the background of the server.
Answer: This would generally be a bad idea, as System.Threading.Timer uses threads from the ThreadPool, the same as ASP.Net.
If for what ever reason your timer delegate blocks or stops, the timer will simply begin a new Thread after the timeout period, which eats in to the Threads available for ASP.net.
If they all begin blocking, effectively you will not be able to serve any more web requests (probably a bad thing)
Answer: That would be dangerous as there can be times when the worker process gets recycled or the AppDomain crashes and the Work Item is killed and you may want it to recover what it was doing, it may not be possible.
A Windows service may be OK if you can get that work item out into a service.  If an HttpContext is required for the work though you may want to have a windows service call a webservice to do the call periodically that may work though likely not ideal.
Answer: That makes sense, but just for fun, what if the work doesn't need to run if the site gets shut down? If it's associated with the Application_Start event and only needs to run while people are browsing the site, what are the risks at that point?
Good answers, I'm just curious a little more about how that works on the inside.
Answer: I would recommend you setup a scheduled task to run a page on your site. I usually point the scheduled task to a .vbs file with the following:

On Error Resume Next
Dim objRequest
Dim URL

Set objRequest = CreateObject("Microsoft.XMLHTTP")
URL = "http://www.mywebsite.com/cron/pagetorun.ashx"

objRequest.open "POST", URL , false

objRequest.Send

Set objRequest = Nothing
Answer: Omar Al Zabir has an excellent post on using cache item callbacks for this purpose.
http://www.codeproject.com/KB/aspnet/ASPNETService.aspx?fid=229682&df=90&mpp=25&noise=3&sort=Position&view=Quick&fr=76&select=1334820

ASP.NET and Timers


Can we measure a electricity? Embedded System?

Question: Checking if electricity is passing through a wire or not using embedded systems. I want to check if power is there or not. I am new to embedded system. If yes how can I check.
Comment: The answer to your question is simply "yes", so you will need to narrow it down by specifying what you need assistance with.
Comment: We can't answer the "how can I check" unless you provide more details about the current (or voltage?) you want to detect.
Answer: By passing through, I presume current flowing.
If it is voltage you are looking for, the previous answer is an exceptionally excellent one.
There are questions one has to ask before a single answer can be given, as above, it depends on the level of involvement of your circuit in the wire you wish to measure.

Measuring the current in a wire with a resistor:
By adding a small resistor to the line you create a little "dam" where the current gets held up a little. This causes a small voltage drop that you can amplify with an op-amp.
Ohm's law for predicting this voltage is: V = I * R
Where V is the voltage you are measuring, I is the current and R is the resistance.
You will need to keep in mind that you are "wasting energy", so with high currents you need a very low resistance, to avoid too high power loss or too much heat.
The power loss can be calculated with: P = I^2 * R
So be sure your resistor can handle P in watts, when you insert I in ampere and R in ohm.

Mesuring the current with no physical intervention:
There are special ways to measure a current in a wire without interfering with the current itself, if you need to. It's a bit more costly and it involves the magnetic effect of current in a wire.
All wires create a magnetic field when a current flows through them.
If your wire conducts AC voltages a simple way is making a signal transformer out of your wire, you loop one or more times through a transformer core (iron, powdered iron or otherwise, depending on frequency) and loop a thin wire on the other side many times. You can now see a small representation of the AC current in the wire in your second winding.
Transformers like these can also be bought outright.
Another way, to measure both AC and DC is what is called a "Hall Effect Current sensor", they measure the minuscule magnetic effect directly and output a voltage representing it, allowing the detection of a DC current as well.
I believe Allegro Microsystems makes some affordable types of these.

Edit:

Be aware that for using a resistor the power flowing through your wire needs to be related to the power of your measurement device, for example they need to share a ground reference.
With transformers and hall-effect sensors you are fully isolated from the current, and so they do not need to be related.
Answer: Assuming the electricity you are measuring does not impact the functionality of your embedded system (i.e. the wire you are measuring is not powering the MCU itself), it's fairly trivial. There are a few methods, and they mostly depend on how isolated you need to be from the line you are measuring.
Digital Read
If you simply want to know if the voltage is above or below a particular threshold, you can wire it up to a digital input on an MCU. The threshold for test can be set to the digital 0/1 threshold of the MCU, or higher (use a potential divider to scale down the voltage you are testing). If test threshold is lower than the MCU's 0/1 threshold, you'll need to amplify the signal with an op-amp or a voltage translator.
Comparator
Use an external comparater, and scale the input voltage using a potential divider as appropriate. The benefit of this method is there is no direct connection between the line you are testing and the MCU. If the voltage is very high, consider using a optically isolated version.
ADC Input
If you want to know the exact voltage level, feed the line into an ADC input of an MCU. Be sure to scale the line level so it never exceeds the MCU's maximum. You can use an opto-isolator for safety if required.
These methods assume the output you want is fed straight into an MCU. You could also feed the output signal to switch something else on (like an LED).
Finally, the simplest method yet is just strapping an LED onto the line for visual inspection of a voltage down the line. Make sure you pick a suitable current limit resistor for the LED specs and the line voltage.


How much in depth should I cover Python?

Question: I'm an undergrad who's studying electronics and fields like data sciences and mostly computing seem most interesting to me but have in-depth knowledge in neither. I learnt basic python last winter vacations and have built on it since then. I'm not too sure how further I should keep doing this and hence wanted to know how beneficial is python to an electronics student (keeping my interests in mind) and should I keep adding to my knowledge?
Comment: Hi 4manshenoy and welcome to scicomp!  While your question is indeed interesting, this really isn't the right forum for this kind of question.  You may have better luck in another forum such as Academia.SE.
Answer: If you understand the basics of Python, you should just try to get your hands dirty using some well known/documented Python libraries for the type of work you want to do.
If you find you don't understand how to use certain features of the libraries due to inadequate knowledge in Python, just study up on those features and then get back to working with the library. Outside of this, it will be hard for any of us to comment on how much more you should learn Python since we don't really know where your skills are at. Good luck.


What is the difference between Uilleann pipes and Great Highland Pipes?

Question: Uilleann pipes being the less famous Irish cousins of the Great Highland Pipes, what exactly is the difference between the two? This question is a variant of this question.
Answer: First the similarities: Both types of bagpipe have a bellows or bladder which is filled by the player blowing air into it. The bellows/bladder is pressed by the player's elbow. The air then goes to three drones, tuned in octaves (two tenor drones tuned in unison and a bass drone an octave lower) and a 'chanter' which the player fingers like a flute.
In the case of the Scottish  Great Highland pipes a bladder holds the air and a simple unkeyed chanter is used, which produces a one-octave mixolydian scale.
In the case of the Irish Uilleann pipes the air is blown by bellows. In addition to the drones there are three additional pipes, known as 'regulators' which have keys and can provide notes or chords as an accompaniment. The chanter is more complex and has keys. It can be overblown and produce two chromatic octaves. The Uilleann pipes have a sweeter, more melodious tone than their Scottish counterparts and are more suited to playing together with other instruments in an ensemble.
Comment: Fun fact: "Uilleann" means "elbow."
Answer: Bag pipe is used for such a wide range of instruments, that any match is more remarkable than a difference.
Criteria are:

base tone (even the octave of it may differ)
number of drones
pitch and interval between them, tunable yes/no
chromatic yes/no (no much more likely, which poses further questions)
range
inflated by mouth piece/bellow
indoor/outdoor volume class
Comment: OK I have made an edit to make clear what I mean.


Do we have access PG&E case files?

Question: Is there any way to have access to PG&E cases in the recent bankruptcy court? Are they public?
Answer: The files are a matter of public record and are available on PACER if you have the case number. Some information is protected and only available to parties (e.g. unredacted copies of exhibits containing account numbers, or social security numbers).
Comment: now how to get the case number? ;)
Answer: While PACER needs a case number, I could find the case number via Google by googling PG&E Bankruptcy PACER, resulting in the result of the US Bankruptcy Court, Northern District of California, telling the case number is 19-30088-DM, jointly administered with 1930089-DM under the Honorable Dennis Montali.
Next stage would be to go to PACER, where you'll need to log in and then enter the case number. Note that PACER does bill you by the documents accessed.
As an alternative source, the docket of close to 12 000 filings (in Feb 2022) can be found on the website of Kroll, who handle this bankruptcy case.

Do we have access PG&E case files?


how to report interest paid

Question: I, as an LLC, purchased a business from an LLC and and it holds the loan on the sale. I need to know do I have to report the interest I pay to original LLC to the IRS on a 1099 or do they have to provide a 1099, or other form, showing the amount of interest they received from me?
Comment: Not sure the answer, but you may find some more people by adding some more tags like "interest", "LLC", or "1099l
Answer: I've not researched this extensively, but my understanding is that you would be required to furnish a 1099-INT to the lending LLC and IRS if you paid at least $600 in interest for the year.  The 1099-INT instructions list a host of exceptions, the primary one that could be applicable here is that you don't issue 1099's to corporations, so if the lending LLC has elected to be taxed as a corporation then you wouldn't issue them a 1099-INT.
If the business purchase included real property then the lending LLC could be required to issue a 1098.
It's worth consulting your tax professional on this one, but regardless of whether or not you are required to furnish a 1099-INT, both parties should keep thorough documentation of payments that show interest and principal paid as it offsets the buyers business income and the interest counts as income to the seller/lender's LLC.
Comment: OP can request a W-9 from the lending LLC. If they check the box "corporation", then OP does not need to send them a 1099-INT.

how to report interest paid


Can I use WGET to generate a sitemap of a website given its URL?

Question: I need a script that can spider a website and return the list of all crawled pages in plain-text or similar format; which I will submit to search engines as sitemap. Can I use WGET to generate a sitemap of a website? Or is there a PHP script that can do the same?
Answer: wget --spider --recursive --no-verbose --output-file=wgetlog.txt http://somewebsite.com
sed -n "s@.\+ URL:\([^ ]\+\) .\+@\1@p" wgetlog.txt | sed "s@&@\&@" > sedlog.txt

This creates a file called sedlog.txt that contains all links found on the specified website. You can use PHP or a shell script to convert the text file sitemap into an XML sitemap. Tweak the parameters of the wget command (accept/reject/include/exclude) to get only the links you need.
Comment: You should add a small delay between requests using `--wait=1`, otherwise it might affect the performance of the site.
Comment: +1 Couldn't quite use it like that as it was giving me a bunch of errors (probably because of different wget/sed versions). But once I did some tweaking, it worked like a charm. Thanks!
Comment: Combined with `tee` https://unix.stackexchange.com/a/128476/312058 you can also see the output in stdout OR `tail -f` is even better
Comment: @Julian Yes, I had the same issue. On macOS, I had to use `gsed` instead of the builtin `sed`. Thanks for the tip!
Answer: You can use this perl script to do the trick : http://code.google.com/p/perlsitemapgenerator/
Comment: It'll generate by scanning file system but won't "crawl". The sites I want to spider are dynamic.