Hi,

today, i had to split a file vertically. I didn't find it in Q&A section, so i made something myself, and post it here because i think it could be usefull for others ? My apologies if it already exists on the site.

I have tab-delimited text files where first column is identifiers and following columns contain data. The aim was to split the file vertically into n files. The bonus is i wanted to shuffle the data columns (ie not conserve the order of the columns in the destination files). For my purpose, i had to repeat the original first column into all destination files, but this can easily be adapted for your purpose.

This is a first try, but i'm quite new to perl, so comments and improvements are welcomed. 
#!/usr/bin/perl -w

# Split a tab-delimited text files into n files, repeating
# first column and shuffling columns.
# Julien Textoris

use strict;
use warnings;

open(IN, "$ARGV[0]");

my $n = $ARGV[1];

#Thanks to Q&A for this !
sub melange_fy {
    my $tab = shift;
    my $i;
    for($i = @$tab; --$i;) {
        my $j = int rand($i+1);
        next if ($i == $j);
        @$tableau[$i,$j] = @$tableau[$j,$i];
    }
}

my $perm =0 ;
my (@ind);

while ( my $ligne = <IN>) {
    $ligne =~ s/[\r\n]//g;
    
    my ($id,@elmt) = split(/\t/, $ligne);
    #make the permutation of tab indices only the first time
        unless($perm++) {
        @ind = (0..@elmt-1);
        melange_fy(\@ind);
    }

    
    my $w = int(scalar(@elmt)/$n+0.5);
    
    for(my $i = 0; $i < $n; $i++) {
        open (OUT, ">>$ARGV[0].$i");
        my $d = $i*$w;
        my($f);
        if($i == $n-1) {
            $f = scalar(@elmt)-1;
        }
            else {
            $f = $d+$w-1;
        }
        
        print OUT join("\t",$id,@elmt[@ind[$d..$f]])."\n";
        
        
        close(OUT);
        
    }
}

[download]
An example input file is : 
Genes    setA    setB    setC    setD    setE    setF    setG
g1    1    2    3    4    5    6    7
g2    1    2    3    4    5    6    7
g3    1    2    3    4    5    6    7

[download]
code is to be launched like :
./vSplit <fileToVSplit> <integer>

<integer> is the number of part you want to split the file into.

Hopes it will help

Marsel

In reply to A vertical (+/- random) split of a file by Marsel

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