CODEWITHSUNDEEP
rfunctiondataframedatasetlapply
user135688
user135688

Reputation: 115

How to create a function read multiple data frames as a list in R

I'm having trouble reading several data files at once. If I want someone to plug in their file directory and have the function read all the files in it, how would I go about it?

I have a folder with 15 files that need to be read. So doing this manually was fine until I decided to use the lapply function - I don't want to use a loop. Here was my code:

files <- list.files(path = "/User/Zoe/Documents etc.....", pattern = ".csv")
all_df <- lapply(files, read.table(file, header = TRUE, fill = TRUE, skip = 1)).

An error shows up saying : 'file' must be a character string or connection. I'm guessing when I use the parameter "files" in lapply it is not the correct type of variable?

Then lastly, how would I be able to create a function of the above (assuming it worked)? I'd go about it like this:

read_all_data <- function(folder_name, dir) {
 files <- list.files(dir, pattern = ".csv")
 all_df <- lapply(files, read.table(file, header = TRUE, fill = TRUE, skip = 1)). 
}

Thanks for the help! The actual reading all files is more important to me than the function!

Upvotes: 0

Views: 1004

Answers (1)

Ronak Shah
Ronak Shah

Reputation: 389055

You have slight syntax error. Either use this :

read_all_data <- function(dir) {
  files <- list.files(dir, pattern = ".csv", full.names = TRUE)
  all_df <- lapply(files, read.table, header = TRUE, fill = TRUE, skip = 1)
  return(all_df)
}

Or with an anonymous function.

read_all_data <- function(dir) {
  files <- list.files(dir, pattern = ".csv", full.names = TRUE)
  all_df <- lapply(files, function(x) 
                   read.table(x, header = TRUE, fill = TRUE, skip = 1))
  return(all_df)
}

Upvotes: 1

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