This post is about pandasql, a Python package we (Yhat) wrote that emulates the R package sqldf. It's a small but mighty library comprised of just 358 lines of code. The idea of pandasql is to make Python speak SQL. For those of you who come from a SQL-first background or still "think in SQL", pandasql is a nice way to take advantage of the strengths of both languages.
In this introduction, we'll show you to get up and running with pandasql inside of Rodeo, the integrated development environment (IDE) we built for data exploration and analysis. Rodeo is an open source and completely free tool. If you're an R user, its a comparable tool with a similar feel to RStudio. As of today, Rodeo can only run Python code, but last week we added syntax highlighting for a bunch of other languages to the editor (markdown, JSON, julia, SQL, markdown). As you may have read or guessed, we've got big plans for Rodeo, including adding SQL support so that you can run your SQL queries right inside of Rodeo, even without our handy little pandasql. More on that in the next week or two!
Start by downloading Rodeo for Mac, Windows or Linux from the Rodeo page on the Yhat website.
ps If you download Rodeo and encounter a problem or simply have a question, we monitor our discourse forum 24/7 (okay, almost).
Behind the scenes, pandasql uses the pandas.io.sql module to transfer data between DataFrame and SQLite databases. Operations are performed in SQL, the results returned, and the database is then torn down. The library makes heavy use of pandas write_frameand frame_query, two functions which let you read and write to/from pandas and (most) any SQL database.
Install pandasql using the package manager pane in Rodeo. Simply search for pandasql and click Install Package.
You can also run ! pip install pandasql from the text editor if you prefer to install that way.
Run the following code to check out the data sets.
Inside Rodeo, you really don't even need the print.variable.head() statements, since you can actually just examine the dataframes directly.
Notice that the plot appears both in the console and the plot tab (bottom right tab).
Tip: You can "pop out" your plot by clicking the arrows at the top of the pane. This is handy if you're working on multiple monitors and want to dedicate one just to your data visualzations.
To keep this post concise and easy to read, we've just given the code snippets and a few lines of results for most of the queries below.
pandas is an incredible tool for data analysis in large part, we think, because it is extremely digestible, succinct, and expressive. Ultimately, there are tons of reasons to learn the nuances of merge, join, concatenate, melt and other native pandas features for slicing and dicing data. Check out the docs for some examples.
Our hope is that pandasql will be a helpful learning tool for folks new to Python and pandas. In my own personal experience learning R, sqldf was a familiar interface helping me become highly productive with a new tool as quickly as possible.
We hope you'll check out pandasql and Rodeo; if you do, please let us know what you think!