将每个data.table列写入R中的单独文本文件

Question

I have a read a csv file into a data.table that is as follows:

      Cat1 Cat2 Cat3   Country   file_name
1:    A    E    B      Canada    first
2:    C    B           India     Second
3:    C                Canada    third
4:    B                Ireland   Fourth
5:    C    A           India     fifth
6:    A    C    F     Canada     Sixth

I am using following code to write the contents of each row to a separate text file:

lapply(1:nrow(df), function(i) write.table(df[i], file= paste0("./TextFiles/", df[i, file_name], ".txt"), row.names = F, col.names = F, quote = F))

The output I am getting right now is as follows for "Sixth.txt" (for example):

A C F Canada Sixth

However, I want the text to be as follows:

Cat1
A

Cat2
C

Cat3
F

Country
Canada

Is there a way to get this output without nesting a lot of lapply ?

Trying the code:

lapply(df, function(i) i)

gives the output:

$Cat1
[1] "A" "C" "C" "B" "C" "A"

$Cat2
[1] "E" "B" ""  ""  "A" "C"

$Cat3
[1] "B" ""  ""  ""  ""  "F"

$Country
[1] "Canada"  "India"   "Canada"  "Ireland" "India"   "Canada" 

$file_name
[1] "first"  "Second" "third"  "Fourth" "fifth"  "Sixth" 

So, I have a feeling it is possible to get the names of the columns before the content and also to insert lines before each column entry. However, I am unable to find a way to do it.

Answer 1

Use apply() function to make each row to a list and then output it using sink() inside for loop. Then check your working directory to see the files File1.txt , File2.txt , File3.txt and File4.txt . Filename can be extracted using strsplit() and can be added to the file output using Result[[i]]$file_name

  library(data.table)
  df <- data.frame(a=1:4,b=9:12,c=3:6,d=0:3)
  df <- data.table(df)

  df
  #    a  b c d
  # 1: 1  9 3 0
  # 2: 2 10 4 1
  # 3: 3 11 5 2
  # 4: 4 12 6 3

  Result = apply(df,1,as.list)


 for(i in 1:length(Result)){
 sink(paste("File",i,".txt",sep=""))
 Result[[i]]$file_name <- strsplit(paste("File",i,".txt",sep=""),"\\.")[[1]][1]
 print(Result[[i]])
 sink()
 }