CODEWITHSUNDEEP
r
maximusyoda
maximusyoda

Reputation: 615

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

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 I used to import the 20 csv files in a directory. Basically, have to combine into a single dataframe.

temp = list.files(pattern = "*.csv")
for (i in 1:length(temp)) assign(temp[i], read.csv(temp[i]))

Upvotes: 24

Views: 34662

Answers (6)

MrFlick
MrFlick

Reputation: 206187

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 stay 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.

Upvotes: 34

MS Berends
MS Berends

Reputation: 5189

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) 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.

A readable version to get TRUEs and FALSEs using R 4 and higher:

ls() |> sapply(get) |> sapply(is.data.frame)

Finally super, super robust, also for package developers:

ls()[sapply(ls(), function(x) is.data.frame(eval(parse(text = x), envir = globalenv())))]

Upvotes: 5

Jonathan Hill
Jonathan Hill

Reputation: 1843

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))))]

Upvotes: 6

Rich Scriven
Rich Scriven

Reputation: 99331

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))

Upvotes: 12

James
James

Reputation: 66834

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))

Upvotes: 7

MentatOfDune
MentatOfDune

Reputation: 309

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.

Upvotes: 7

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