Assign names stored in a file to numbers stored in a second file

Question

I have two files:

>head(fileA)
   2    1   544.8  1279.2   1.0603  3.2460  0.0542 
   3    1   546.2  1277.8   1.0463  3.2460  0.0553 
   3    2   543.9  1280.1   0.1652  3.2460  0.0177 
   4    1   543.7  1280.3   1.0819  3.2460  0.0527 
>head(fileB)
1 Coly
2 Mony
3 Fong
4 Wow
5 Poly

I would like to assign the names in fileB to the number in fileA, to get the following output

   2 Mony   1 Coly   544.8  1279.2   1.0603  3.2460  0.0542 
   3 Fong   1 Coly  546.2  1277.8   1.0463  3.2460  0.0553 
   3 Fong   2 Mony  543.9  1280.1   0.1652  3.2460  0.0177 
   4 Wow    1 Coly   543.7  1280.3   1.0819  3.2460  0.0527 

To be honest I was not able to try anything, I just spent a lot of time looking up how to do this. The only thing that I thought about was to assign the numbers in fileA to variables and then every time this variables are found append to it the content of fileB. Unfortunately, I do not know how to do this.

Any suggestion, link, directive? Thanks

Answer 1

You can use bash's read, and grep and tr:

cat fileA | while read i j k ; do
  grep "^$i\W" fileB | tr '\n' ' '
  grep "^$j\W" fileB | tr '\n' ' ' 
  echo $k 
done

Answer 2

Perl to the rescue!

#! /usr/bin/perl
use warnings;
use strict;

open my $B, '<', 'B' or die $!;
my %name_of;
while (<$B>) {
    my ($num, $name) = split;
    $name_of{$num} = $name;
}

open my $A, '<', 'A' or die $!;
while (<$A>) {
    my @F = split;
    splice @F, 2, 0, $name_of{ $F[1] };
    splice @F, 1, 0, $name_of{ $F[0] };
    print "@F\n";
}

The second paragraph reads the B file into a hash table, mapping numbers to names. The third paragraph reads the A file, splits each line into an array, inserts the names retrieved from the hash table according to the first two columns into the array, and prints it.