Read all files in a directory into R

list.files( ) + assign( )

# general demo

setwd('~/Documents/directory_of_csv_files/')

# create a collection of .csv files names following some system

X <- expand.grid(LETTERS,1:10)

for(i in 1:nrow(X)){
  Data.i <- data.frame(matrix(data = rnorm(1000), nrow = 10))
  colnames(Data.i) <- paste(X[i,1], X[i,2], 'C',1:ncol(Data.i), sep='.')
  name.i <- paste(paste('Boring_Bit_of_File_Name', X[i,1], X[i,2], sep = '_'), 'csv', sep = '.')
  write.csv(file = paste(name.i), x = Data.i)
}

rm(list = ls()) # clear the workspace

ls()

# read the list of file names in the specified directory into a character vector

file.names <- list.files(path = '~/Documents/directory_of_csv_files/')
​
# read in each file in the directory naming it with the interesting bit of the filename

for(i in 1:length(file.names)){
  start.stripped.i <- unlist(strsplit(x = file.names[i], split = 'Boring_Bit_of_File_Name_'))[2]
  obj.name.i <- unlist(strsplit(x = start.stripped.i, split = '\\.'))[1] # escape character before . so it's not treated as a wildcard 
  X.i <- read.csv(file.names[i])
  assign(x = obj.name.i, value = X.i)
  rm(list = c('start.stripped.i', 'obj.name.i', 'X.i'))
  gc()
}

ls()