How can I make a list of all dataframes that are in my global environment?

Question

I am trying to use rbind on them. But I need a list of all the dataframes that are already in my global environment. How can I do it?

Code

Answer 1

From your posted code, I would recommend you start a new R session, and read the files in again with the following code

do.call(rbind, lapply(list.files(pattern = ".csv"), read.csv))

Answer 2

To improve MentatOfDune's answer (great username by the way):

ls()[sapply(ls(), function(x) any(class(get(x)) == 'data.frame'))]

or even more robust:

ls()[sapply(ls(), function(x) any(is.data.frame(get(x))))]

This also supports tibbles (created with dplyr for example), because they contain multiple classes, where data.frame is one of them.

Answer 3

The ls function lists all things in your environment. The get function gets a variable with a given name. You can use the class function to get the class of a variable.

If you put them all together, you can do this:

ls()[sapply(ls(), function(x) class(get(x))) == 'data.frame']

which will return a character vector of the data.frames in the current environment.

Answer 4

This function should return a proper list with all the data.frames as elements

dfs <- Filter(function(x) is(x, "data.frame"), mget(ls()))

then you can rbind them with

do.call(rbind, dfs)

Of course it's awfully silly to have a bunch of data.frames lying around that are so related that you want to rbind them. It sounds like they probably should have been in a list in the first place.

I recommend you say away from assign(), that's always a sign things are probably afoul. Try

temp <- list.files(pattern="*.csv")
dfs <- lapply(temp, read.csv)

that should return a list straight away.

Answer 5

This is a slight improvement on MentatOfDune's answer, which does not catch data.frames with multiple classes:

ls()[grepl('data.frame', sapply(ls(), function(x) class(get(x))))]

Answer 6

If you only have data.frames with the same number of columns and column names in you global environment, the following should work (non-data.frame object don't matter):

do.call(rbind, eapply(.GlobalEnv,function(x) if(is.data.frame(x)) x))