Split single column of csv horizontally in bash into multiple smaller csv files in BASH

Question

I am using bash and I have a single column (not row) in csv with no headers- samplefile.csv

111 
222 
333 
444 
555 
666 
777 
888

I am looking to split this into (say)2 csv files of 4 rows and a single column each in this case (if odd number say 9 rows then 5 and 4) csv files with data

output1.csv (1 column 4 rows)

111
222
333
444

and output2.csv (1 column and 4 rows)

555
666
777
888

Csplit does not create csv files as shown here split a file into x files where file names are numbered

Any suggestions?

Answer 1

This is simple with awk try awk '{print $0 > ("output"i+1".csv")}!(NR%4){i++}' file .

Demo:

$ ls 
file

$ cat file 
111 
222 
333 
444 
555 
666 
777 
888

$ awk '{print $0 > ("output"i+1".csv")}!(NR%4){i++}' file

$ ls
file  output1.csv  output2.csv

$ cat output1.csv 
111 
222 
333 
444 

$ cat output2.csv 
555 
666 
777 
888

Explanation:

The modulus operator is key here, we want to split the input line after every fourth line:

$ awk '{print NR%4,$0}' file
1 111
2 222
3 333
0 444
1 555
2 666
3 777
0 888

The modulus (remainder) of four at every fourth is of course zero so we use this fact to increment the file counter. !(NR%4) is shorthand for NR%4==0 as zero evaluates as false and NR%4 is zero when we want the block {i++} to execute so we negative it.

$ awk '{print NR%4,$0,"output"i+1".csv"}!(NR%4){i++}' file
1 111 output1.csv
2 222 output1.csv
3 333 output1.csv
0 444 output1.csv
1 555 output2.csv
2 666 output2.csv
3 777 output2.csv
0 888 output2.csv

Answer 2

what are you looking for is just split command, with -n option

split -nl/2 input output

will do the job for you.

from split man page:

-n, --number=CHUNKS
              generate CHUNKS output files.  See below
 CHUNKS may be: N       split into N files based on size of input K/N     output Kth of N to stdout l/N     split into N  files  without  splitting  lines  l/K/N
       output Kth of N to stdout without splitting lines r/N     like 'l' but use round robin distribution r/K/N   likewise but only output Kth of N to stdout

Answer 3

This worked for me. I opened the resulting csv in excel and it was formatted correctly. I haven't yet figured out how to remove the trailing comma, but that seems acceptable based on many csv format definition. The first xargs call adds a comma to each line of the file. The second xargs batches four together. If you redirect that to a file (> new.csv) it may be what you are looking for.

>cat my.csv
111
222
333
444
555
666
777
888 
>cat my.csv | xargs -n 1 -i echo \{\}, | xargs -n 4 
111, 222, 333, 444,
555, 666, 777, 888,

Answer 4

I you can use split command.

n= awk 'END{print int(NR/2)}' file_name && split -l $n file_name

cat output1
111
222
333
444


cat output2 
555
666
777
888