How to append a special character in awk? - linux

Question

I have three files with different column and row size. For example,
ifile1.txt ifile2.txt ifile3.txt
1 2 2 1 6 3 8
2 5 6 3 8 9 0
3 8 7 6 8 23 6
6 7 6 23 6 44 5
9 87 87 44 7 56 7
23 6 6 56 8 78 89
44 5 76 99 0 95 65
56 6 7 99 78
78 7 8 106 0
95 6 7 110 6
99 6 4
106 5 34
110 6 4
Here ifile1.txt has 3 coulmns and 13 rows,
ifile2.txt has 2 columns and 7 rows,
ifile3.txt has 2 columns and 10 rows.
1st column of each ifile is the ID,
This ID is sometimes missing in ifile2.txt and ifile3.txt.
I would like to make an outfile.txt with 4 columns whose 1st column would have all the IDs as in ifile1.txt, while the 2nd coulmn will be $3 from ifile1.txt, 3rd and 4th column will be $2 from ifile2.txt and ifile3.txt and the missing stations in ifile2.txt and ifile3.txt will be assigned as a special charecter '?'.
Desire output:
outfile.txt
1 2 6 ?
2 6 ? ?
3 7 8 8
6 6 8 ?
9 87 ? 0
23 6 6 6
44 76 7 5
56 7 8 7
78 8 ? 89
95 7 ? 65
99 4 0 78
106 34 ? 0
110 4 ? 6
I was trying with the following algorithm, but can't able to write a script.
for each i in $1, awk '{printf "%3s %3s %3s %3s\n", $1, $3 (from ifile1.txt),
check if i is present in $1 (ifile2.txt), then
write corresponding $2 values from ifile2.txt
else write ?
similarly check for ifile3.txt

Answer 1

You can do that with GNU AWK using this script:
script.awk
# read lines from the three files
ARGIND == 1 { file1[ $1 ] = $3
# init the other files with ?
file2[ $1 ] = "?"
file3[ $1 ] = "?"
next;
}
ARGIND == 2 { file2[ $1 ] = $2
next;
}
ARGIND == 3 { file3[ $1 ] = $2
next;
}
# output the collected information
END { for( k in file1) {
printf("%3s%6s%6s%6s\n", k, file1[ k ], file2[ k ], file3[ k ])
}
}
Run the script like this: awk -f script.awk ifile1.txt ifile2.txt ifile3.txt > outfile.txt