Combine information from two files, line by line

Question

I have 2 files as input:

File 1 (space separated)

ID POS a0 a1
SNP1 123 A C
SNP2 456 T C
SNP3 789 G A

File 2 (space separated)

0 1 0 1 0 0 0 1
1 1 0 0 1 0 0 1
0 1 1 1 0 0 0 1

Required output

A C A C A A A C
C C T T C T T C
G A A A G G G A 

Each line in file 2 represent 1 Line in File 1, the trick is to substitute the 0 and 1 for the corresponding letter in a0 and a1 respectively. This is just a small example, the real file is huge, more than 600K lines.

I am looking for an awk or perl solution.

Answer 1

As an illegible awk one-liner

$ awk 'NR>1{a[0]=$3;a[1]=$4;getline<f;for(i=1;i<=NF;i++)$i=a[$i];print}' f=file2 file1
A C A C A A A C
C C T T C T T C
G A A A G G G A

More readable:

awk '
    # skip the header in file1
    NR == 1 {next}
    {
        # read the values from the file1 line
        a[0] = $3
        a[1] = $4

        # replace the current record with the corresponding line from the map file
        getline < map_file

        # and now substitute the 0/1 with the values
        for (i=1; i<=NF; i++)
            $i = a[$i]
        print
    }
' map_file=file2  file1

Answer 2

You can do this fully in awk but as a variation here's an awk + paste solution. You'll need bash or another shell that supports process substitution

paste <(tail -n +2 file1) file2 | 
awk '{a["0"]=$3; a["1"]=$4; for (i=5; i<=NF; ++i) printf "%s%s", a[$i], i==NF?"\n": " "}'

The tail -n +2 is needed to skip the header line from file1.

Answer 3

#!/usr/bin/env perl
# TODO docs on usage here, or write perldocs below, etc.
use strict;
use warnings;

die "Usage: $0 headerfile datafile\n" if @ARGV != 2;

my ($headerfile, $datafile) = @ARGV;

open(my $hfh, '<', $headerfile) or die "could not open '$headerfile': $!\n";
open(my $dfh, '<', $datafile) or die "could not open '$datafile': $!\n";

readline $hfh; # skip the header line

my $lineno = 1;
while (!eof($hfh) and !eof($dfh)) {
  my $convert_to = join '', (split ' ', scalar readline $hfh)[-2,-1];
  die sprintf "no conversion at $headerfile:%d\n", $lineno+1
    if !defined $convert_to;

  $_ = readline $dfh;
  die "no data to convert at $datafile:$lineno\n" if !defined;

  eval "tr/01/$convert_to/, 1" or die $@;
  print;

  $lineno++;
}