fasoli has asked for the wisdom of the Perl Monks concerning the following question:

Hello dear monks! I've been driving myself crazy over the code below, I can't figure out how to make it run properly :( The files that I'm trying to match are in the style of AC0001_F00001_S00001.tpr, AC0002_F00002_S00001.tpr, AC0003_F00003_S00001.tpr etc. AC goes from 1 to 50 (so AC0001 to AC0050) and frames go from F00001 to F00020.

So what I'm doing is: I'm putting all my tpr files in an array, then I match their names and then I want to say "for molecule 1 to 2" and "for frame 1 to 2" -> print what files you are finding. However what happens is that, because of the foreach loop, the script print the files that it finds 6 times in total, which is exactly how many tpr files I have. I have tried closing the foreach loop earlier, before the for loops, but that makes no sense. Is there a syntax error? Or am I using the loops totally wrong?

#!/usr/bin/perl/

use strict;
use warnings;

my $tpr = "tpr";

my $id;
my $filepath;
my $batch;
my $number;
my $molec;
my $frame;
my $mdstep;

my @tpr;
@tpr = `ls *.tpr`;

print "Script start \n";
print "\n";

foreach (@tpr) {
   
  /(\w{2})(\d{4})_F(\d{5})_S(\d{5})/;

  $id = "AC";
  $molec = $2;
  $frame = $3;
  $mdstep = $4;

    for ($molec=2; $molec<=2; $molec++) { 
      for ($frame=1; $frame<=2; $frame++) {

       my $molecform = sprintf ("%04d", $molec);
       my $frameform = sprintf ("%05d", $frame);    
       print "$id${molecform}_F${frameform}_S${mdstep}\.$tpr \n";
       }
     
   }
} # end of loop through tpr files

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Re: foreach loop running too many times...?
by choroba (Cardinal) on Feb 10, 2016 at 20:23 UTC
    You assign capture groups to $molec and $frame, but never use the assigned values. Instead, you change their values in the loops.

    Unrelated comments:

    • Declaring all the variables at the start is needed in Pascal, not Perl. Use the smallest possible scope.
    • No need to call ls: 
      @tpr = `ls *.tpr`;

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      could be written in a more Perlish way as 

      @tpr = glob '*.tpr';

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    ($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

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Re: foreach loop running too many times...?
by poj (Abbot) on Feb 10, 2016 at 20:51 UTC

    Match the values you want with a regex

    #!perl
use strict;

my @tpr = qw(
AC0001_F00001_S00011.tpr 
AC0001_F00002_S00012.tpr 
AC0001_F00003_S00013.tpr
AC0002_F00001_S00021.tpr 
AC0002_F00002_S00022.tpr 
AC0002_F00003_S00023.tpr
AC0003_F00001_S00031.tpr 
AC0003_F00002_S00032.tpr 
AC0003_F00003_S00033.tpr);
             
foreach (@tpr) {
   
  if (/(\w{2})(\d{4})_F(\d{5})_S(\d{5})/){

    my $id = "AC";
    my $molec  = $2;
    my $frame  = $3;
    my $mdstep = $4;

    # molecule 1 to 2 and frame 1 to 2
    if ( ($molec =~ /000[12]/) && ($frame =~ /0000[12]/) ){ 
      print "$_\n";
    }
  } 
  
} # end of loop through tpr files

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