Combining multiple .csv files into a single data.frame in R in one line of code

read_mult_csv.R

library(readr)
library(dplyr)
library(purrr)
#create data for testing
split_cars <- mtcars |> 
  group_by(cyl) |> 
  group_split()

tmp <- tempdir()

write_csv(split_cars[[1]], file.path(tmp, "mtcars1.csv"))
write_csv(split_cars[[2]], file.path(tmp, "mtcars2.csv"))
write_csv(split_cars[[3]], file.path(tmp, "mtcars3.csv"))

# Make a vector of file paths
files <- list.files(tmp, pattern = "mtcars*", full.names = TRUE)
files

# Three options for reading in data from multiple files in one line
# Use purrr::map_df() to iterate
df <- map_df(files |> set_names(files), \(x) read.csv(x), .id = "filename")
nrow(df)
# use read_csv()
df <- read_csv(files, id = "filename")
nrow(df)
# use the arrow package (opens as something like a database connection---good for when you have so many files they don't all fit into memory)
library(arrow)
df <- open_dataset(files, format = "csv")
nrow(df)