Write file with 2 columns using shell script

Question

How can I print variables to an output file in two or more columns (using echo for example). I have the following:

grep -oP 'value\s*=\s*\K.*' file >x_vs_y  # x values

for X in $(seq 0 50 400)
do
   echo  "$X"  >>x_vs_y    # y values
done

Output: (x_vs_y)

1.08759432363
1.08477216702
1.08211988431
1.07947977045
1.07685185457
1.07423631941
1.07163282502
1.06904156798
1.06646245052
0
50
100
150
200
250
300
350
400

With this script I get an output file in a single column (18x1), but I want to get a 9x2 array (X vs Y) like:

Output: (x_vs_y)

1.08759432363 0
1.08477216702 50
1.08211988431 100
1.07947977045 150
1.07685185457 200
1.07423631941 250
1.07163282502 300
1.06904156798 350
1.06646245052 400

Answer 1

Consider this input file:

$ cat file
value = 1.08759432363
value = 1.08477216702
value = 1.08211988431
value = 1.07947977045
value = 1.07685185457
value = 1.07423631941
value = 1.07163282502
value = 1.06904156798
value = 1.06646245052

To print two columns:

$ awk '{print x+0, $3; x+=50}' file
0 1.08759432363
50 1.08477216702
100 1.08211988431
150 1.07947977045
200 1.07685185457
250 1.07423631941
300 1.07163282502
350 1.06904156798
400 1.06646245052

Saving the output in a file

$ awk '0==a[$0]++' file >outfile
$ cat outfile
value = 1.08759432363
value = 1.08477216702
value = 1.08211988431
value = 1.07947977045
value = 1.07685185457
value = 1.07423631941
value = 1.07163282502
value = 1.06904156798
value = 1.06646245052

Answer 2

Maybe a combination of paste and seq can be simpler:

paste datafile <( seq 0 50 $(( ($(wc -l datafile | cut -d' ' -f1 )-1)*50 )) )  > output

The last value for seq is just based on the line numbers in your input datafile.