Q:

Issue matching string in list

I am trying to see if a list contains a particular string but I am having an issue.
> k
[1] "Investment"
> t
[[1]]
[1] "Investment"     "Non-Investment"

> class(k)
[1] "character"
> class(t)
[1] "list"
> k %in% t
[1] FALSE

should not the above code result in TRUE rather than FALSE?

A:

You need to unlist the list:
X <- "investment"
Y <- list(c("non-investment", "investment"))

X %in% unlist(Y)

Note I've changed it to X and Y: t is a base function so it's best not to overwrite it because it might cause conflicts!
One thing to consider is lists with multiple vectors, and figuring out whether you want to be searching across a list of vectors, or within a specific vector. Then you can use unlist to check all vectors simultaneously, and the square brackets to check a specific vector. To illustrate this, here there are sublists in Y, and the X string is in the second list, unlist tells us that X is in Y, while Y[[1]] returns FALSE, because %in% is only checking the first sublist:
X <- "alpha"
Y <- list(c("non-investment", "investment"), c("alpha", "beta"))

X %in% unlist(Y)
X %in% Y[[1]]

Note that, if you had specified Y as just a vector - which is essentially what it is in your example because there are not other sublists - then you could just use:
X <- "investment"
Y <- c("non-investment", "investment")
X %in% Y

A:

The problem with t is it is a length one list of vectors - try k %in% t[[1]]. You may want to use unlist().
EDIT Sorry, list of vector, not lists.

