CODEWITHSUNDEEP
regexperl
Imii Iik
Imii Iik

Reputation: 205

Perl: search index of element using regex

I have a file that contains several columns separated with \t, and I want to get the position (index) of some columns by using regular expressions to specify the name of header of columns. Here is my code, but I can't search using regular expressions:

#!"C:\xampp\perl\bin\perl.exe"
my %dic;
my %index;
while(<>) {
    my @array2 = split(/\t/, $_);
    @index{@array2} = (0..$#array2);

    my $column13= $index{"name13"};// Here I want to search  using regex
    my $column17= $index{"name17"};// Here I want to search  using regex
    my $column21= $index{"name21"};// Here I want to search  using regex
    my $column34= $index{"name32"};// Here I want to search  using regex
    my $column43= $index{"name43"};// Here I want to search  using regex

    print $array2[$column13]$.",".$array2[$column17].",".$array2[$column21].
          ",".$array2[$column34].",".$array2[$column43]."\n"; 
}

For example the value of $columns13 should be 12 (position 12) and:

 $column17 = 16
 $column21 = 20
 $column34 = 33
 $column43 = 42

My input is a file that contains several columns separated with \t:

name1   name2   name3...    name85
1   2   3       4   ....     765
6   5   9       67  ....      8768
87  787 767     7687 ......   8768

My output should contains only the colums that have been searched:

name13  name17  name21...   name43
    876 76  87      4  .... 87687
   787  987 9       67  ...  87686
    53  765 767     7687 .... 8686

Upvotes: 1

Views: 98

Answers (1)

Borodin
Borodin

Reputation: 126722

You're specification is rather sloppy, but I think this will do as you ask. It takes the first non-blank line from the input as the header line, and creates a list of corresponding indices in @indices. The corresponding columns from each subsequent are printed to STDOUT.

use strict;
use warnings;

my @selection = qw(
    name1
    name3
    name85
);

my @indices;

while (<>) {
  next unless /\S/;
  chomp;
  my @fields = split /\t/;

  unless (@indices) {
    @indices = grep {
      my $i = $_;
      grep { $fields[$i] =~ /$_/ } @selection;
    } 0 .. $#fields;
  }

  print join("\t", @fields[@indices]), "\n";
}

Upvotes: 1

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