How to add a column containing a single value to a csv file in Linux-CodePudding

I have a csv file with a header (first line) that looks like this

"Gene1","Gene2"
"G1","G2"
"G2","G8"

I want to add a column to this file containing number 9 so the file looks like this. I need the column name of the new column to be "Score" and the value throughout is 9

"Gene1","Gene2","Score"
"G1","G2",9
"G2","G8",9

I tried this code with awk but it is naming column 9, I want its name to be "Score" how do I do this?

awk -F ',' -v OFS=',' '{ $(NF 1) = 9; print }' infile.csv > outfile.csv

How can I do this in shell? Thank you!

CodePudding user response：

Adding a ternary operation to OP's current code to conditionally determine the new field value based on the current record number (NR):

awk -F ',' -v OFS=',' '{ $(NF 1) = (NR==1 ? "\"Score\"" : 9); print }' infile.csv

This generates:

"Gene1","Gene2","Score"
"G1","G2",9
"G2","G8",9

CodePudding user response：

Another shorthand awk solution:

awk '{print $0 "," (NR==1 ? "\"Score\"" : 9)}' file

"Gene1","Gene2","Score"
"G1","G2",9
"G2","G8",9

Or a sed solution:

sed '1s/$/,"Score"/;1!s/$/,9/' file

"Gene1","Gene2","Score"
"G1","G2",9
"G2","G8",9

CodePudding user response：

With your shown samples and attempts, please try following awk code. We need to put a separate condition for 1st line to handle headers in it then rest of the lines can be added addiotnal field in current line which is 9 in value then simply print the line.

awk 'BEGIN{FS=OFS=","} FNR==1{print $0,"\"Score\"";next} {$(NF 1)="9"} 1' Input_file

CodePudding user response：

$ awk -F, -v OFS=, 'NR==1 ? $  NF="\"Score\"" : $  NF=9' file
"Gene1","Gene2","Score"
"G1","G2",9
"G2","G8",9