How to export multiple list of dataframes from R

Question

I want to export all dataframes from my list of 3 lists to separate '.txt' files. I have a list 'my_list' containing 3 lists (list1, list2 and list3).

Each list contain multiple dataframes. I want to export all dataframes for the 3 lists to separate files ( r1_df1.txt , r1_df2.txt , r2_df3.txt , r2_df4.txt , r2_df5.txt , r3_df6.txt , r3_df7.txt , r3_df8.txt )

Let create some dataframes:

df1 <- data.frame(geneName = 1:3, EnsemblID = 4:6, position = c(654654654,654654,654654))
df2 <- data.frame(id = 1:3, sex = c("M", "F", "T"))
df3 <- data1 <- data.frame(x1 = 1:3, x2 = letters[1:3])
df4 <- data.frame(y1 = c(3, 2, 1), y2 = c(6, 5, 4))
df5 <- data.frame(geneName = 1:3, EnsemblID = 4:6, position = c(65465,654654,987987))
df6 <- data.frame(id = 1:3, sex = c("C", "S", "T"))
df7 <- data1 <- data.frame(x1 = 1:3, x2 = letters[1:3])
df8 <- data.frame(z1 = c(3, 45, 1), p2 = c(6, 5, 4))

dataframes in a list

list1 <- list(df1, df2); names(list1) <- c("df1", "df2")
list2 <- list(df3,df4,df5); names(list2) <- c("df3", "df4", "df5")
list3 <- list(df6, df7, df8); names(list3) <- c("df6", "df7", "df8")

my_list contain the 3 lists

my_list <- list(list1, list2, list3); names(my_list) <- c("r1", "r2", "r3")

Export dataframes to separate .txt files**

for one list I use this code

lapply(seq_along(list1),
       function(i) write.table(list1[[i]], 
                               paste0("r1_", names(list1)[i] , ".txt"),
                               row.names = FALSE, quote = FALSE, sep = "\t", dec = ","))

## r1_df1.txt
## r1_df2.txt
                           

How can I do the same thing for all lists at once?

I tried for loop

for (i in seq_along(my_list)) {
    filename = paste("r_", names(my_list)[i], ".txt")
    write.table(my_list[[i]], filename, row.names = FALSE, quote = FALSE, sep = "\t", dec = "," )
}
    

I get 3 files, each one with bind dataframes and not separate dataframes.

Answer 1

It would be easier to do this if you iterate over names and the data at the same time.

Try this with purrr :

library(purrr)

imap(my_list, function(x, y) imap(x, 
           ~write.table(.x, paste0(y, '_', .y , ".txt"),
            row.names = FALSE, quote = FALSE, sep = "\t", dec = ",")))

Or if you want to keep things in base R :

Map(function(x, y) {
  Map(function(p, q) {
    write.table(p, paste0(y, '_', q , ".txt"),
               row.names = FALSE, quote = FALSE, sep = "\t", dec = ",")
  }, x, names(x))
}, my_list, names(my_list))

Answer 2

You might want to unlist not recursively beforehand.

my_list.u <- unlist(my_list, recursive=F)
for (i in seq_along(my_list.u)) {
    filename=paste0("r_", names(my_list.u)[i], ".txt")
    write.table(my_list.u[[i]], filename, row.names=FALSE, quote=FALSE, 
                sep="\t", dec="," )
}

Or without for loop using sapply which is around 20% faster.

sapply(seq(my_list.u), function(x) 
  write.table(my_list.u[[x]], paste0(names(my_list.u)[x], ".txt"),
              row.names=FALSE, quote=FALSE, sep="\t", dec=","))