CODEWITHSUNDEEP
bashshellawk
drk
drk

Reputation: 271

Shell script to combine three files using AWK

I have three files G_P_map.txt, G_S_map.txt and S_P_map.txt. I have to combine these three files using awk. The example contents are the following -

(G_P_map.txt contains)

test21g|A-CZ|1mos
test21g|A-CZ|2mos
 ...

(G_S_map.txt contains)

nwtestn5|A-CZ
nwtestn6|A-CZ
 ...

(S_P_map.txt contains)

3mos|nwtestn5
4mos|nwtestn6

Expected Output :

1mos, 3mos
2mos, 4mos

Here is the code which I tried. I was able to combine the first two, but I couldn't do along with the third one. 

awk -F"|" 'NR==FNR {file1[$1]=$1; next} {$2=file[$1]; print}' G_S_map.txt S_P_map.txt

Any ideas/help is much appreciated. Thanks in advance!

Upvotes: 2

Views: 902

Answers (2)

Dennis Williamson
Dennis Williamson

Reputation: 360105

GNU AWK (gawk) 4 has BEGINFILE and ENDFILE which would be perfect for this. However, the gawk manual includes a function that will provide this functionality for most versions of AWK.

#!/usr/bin/awk

BEGIN {
    FS = "|"
}

function beginfile(ignoreme) {
    files++
}

function endfile(ignoreme) {
    # endfile() would be defined here if we were using it
}

FILENAME != _oldfilename \
{
    if (_oldfilename != "")
        endfile(_oldfilename)
    _oldfilename = FILENAME
    beginfile(FILENAME)
}

END   { endfile(FILENAME) }

files == 1 {    # save all the key, value pairs from file 1
    file1[$2] = $3
    next
}

files == 2 {    # save all the key, value pairs from file 2
    file2[$1] = $2
    next
}

files == 3 {    # perform the lookup and output
    print file1[file2[$2]], $1
}    

# Place the regular END block here, if needed. It would be in addition to the one above (there can be more than one)

Call the script like this:

./scriptname G_P_map.txt G_S_map.txt S_P_map.txt

Upvotes: 2

Brian Agnew
Brian Agnew

Reputation: 272297

I would look at a combination of join and cut.

Upvotes: 3

Related Questions