How to add columns to a file based on matched column and maintain the order of lines using awk

Question

How can I match a column from a file to next file and append the columns if present using awk.

File 1:

T36 T200 T77 T99 T100 T101 T110

File2:

T36 aa 123 T36 aa 456 T200 cc 789 T99 aa 1011 T77 bb 1213 T77 bb 1415 T100 xx 1617

Desired output:

T36 aa 123 T36 aa 456 T200 cc 789 T77 bb 1213 T77 bb 1415 T99 aa 1011 T100 xx 1617 T101 T110

In my output file I want to get the order of file 1 and also print the lines that are not present in file 2.

So far I have done this but it is printing only the matched columns not all.

awk 'NR == FNR { x[$1]=$1; next} { print x[$1], $0 }' file1 file2

Please Help!

(1) you have to parse file2 first and later file1 (2) You have to save multiline string for every key, that means appending to exisitng value, (depending on a conditional expression) and not overwriting (3) when printing, again a ternary is needed because you want to print the key if there is no value. — thanasisp
– thanasisp, Commented Jun 10, 2022 at 22:15

thanasisp · Accepted Answer · 2022-06-10 22:12:03Z

2

awk 'f==2 {map[$1] = ($1 in map) ? map[$1] ORS $0 : $0} f==1 {print (($1 in map)? map[$1] : $1)} ' f=2 file2 f=1 file1

or the same using the FNR==NR idiom:

awk 'FNR==NR {map[$1] = ($1 in map) ? map[$1] ORS $0 : $0; next} {print (($1 in map)? map[$1] : $1)} ' file2 file1

Output:

T36 aa 123 T36 aa 456 T200 cc 789 T77 bb 1213 T77 bb 1415 T99 aa 1011 T100 xx 1617 T101 T110

answered Jun 10, 2022 at 22:12

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