CODEWITHSUNDEEP
rreadr
SiH
SiH

Reputation: 1546

read csv file from list but add the filename as identifier

I have list of csv files. I could read them all using read_csv.

But I would like to add the filename as identifier. How do I do it ?

library(tidyverse)

# read file names
csv_filenames <- list.files(path = "OMITTED FOR THIS EXAMPLE", 
                            full.names = TRUE)


###
csv_filenames are "One.csv", "Two.csv", "Three.csv", ....
###

# read csv files
df <- read_csv(csv_filenames)

Upvotes: 0

Views: 681

Answers (5)

jay.sf
jay.sf

Reputation: 72838

Just cbind the basenames, actually.

lapply(csv_filenames, \(x) cbind(read.csv(x), file=basename(x))) |> do.call(what=rbind)
#   X1 X2 X3 X4      file
# 1  1  4  7 10 file1.csv
# 2  2  5  8 11 file1.csv
# 3  3  6  9 12 file1.csv
# 4  1  4  7 10 file2.csv
# 5  2  5  8 11 file2.csv
# 6  3  6  9 12 file2.csv
# 7  1  4  7 10 file3.csv
# 8  2  5  8 11 file3.csv
# 9  3  6  9 12 file3.csv

Data:

dat <- data.frame(matrix(1:12, 3, 4))
path <- '/what/so/ever'
lapply(1:3, \(i) write.csv(dat, paste0(path, '/tmp/file', i, '.csv'), row.names=F))
csv_filenames <- list.files(paste0(path, "/tmp"), full.names=TRUE)

Upvotes: 0

Jilber Urbina
Jilber Urbina

Reputation: 61154

With R base

csv_files <- lapply(csv_filenames, read.csv)
file_names <- sub("\\..*", "", basename(csv_filenames))
out <- lapply(1:length(csv_files), function(i){
  transform(csv_files[[i]],  file_name = file_names[i])
})
do.call(rbind, out)

Upvotes: 1

neilfws
neilfws

Reputation: 33782

read_csv has an argument id = ; if you specify "path", you get a column named "path" with the file names:

csv_data <- read_csv(csv_filenames, id = "path")

If you wanted just the base file name, you could add a dplyr::mutate step:

library(dplyr)
csv_data <- read_csv(csv_filenames, id = "path") %>%
  mutate(path = basename(path))

Upvotes: 1

Achal Neupane
Achal Neupane

Reputation: 5719

library(dplyr)

# list of file names
file_list <- list.files(path = "path/to/csv/files", pattern = "*.csv")

# read in all files and add the file name as an additional column
data_list <- lapply(file_list, function(x) {
  data <- read.csv(file = x, stringsAsFactors = FALSE) %>%
    mutate(file_name = x)
  return(data)
})

Upvotes: 1

jpsmith
jpsmith

Reputation: 17240

You should be able to use assign with basename in a for loop.

for(i in seq_along(csv_filenames)){
  assign(basename(csv_filenames)[i], read.csv(csv_filenames[i]))
}

Using basename will assign a new object in the global environment with the name of the file in the folder (not the whole file path obtained with full.names = TRUE).

Upvotes: 1

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