in reply to What can I do to improve my code - I'm a beginner

Hello Anonymous Monk,

Some commends that could improve the speed of your script. Unfortunately I do not have the time to review it all and commend as many things I could suggest (sorry for that) but with a quick look:

Regarding your while loop. Since you are using a while loop (meaning that automatically) will read one line at a time you are assigning next line and repeating the same process for the first 12 lines, why not use also an if condition based on line number. Sample bellow:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %HoA;
while (<>) {
    chomp;
    if ( $. <= 12 ) {
    if (index($_, ',') != -1) {
        my @fields = split(/,/, );
        push @{ $HoA{$fields[0]} }, @fields;
            $. = 0 if $. == 12; # reset line number
    }
    else {
        warn "Line could not be parsed: $_\n";
    }
    }
} continue {
    close ARGV if eof;
}

print Dumper \%HoA;

__END__

$ perl test.pl test.csv
$VAR1 = {
          'Anand' => [
                       'Anand',
                       '1',
                       '2',
                       '3',
                       '4',
                       'xyz',
                       'Anand',
                       '2',
                       '3',
                       '4',
                       '5',
                       'wer',
                       'Anand',
                       '3',
                       '4',
                       '4',
                       '4',
                       'ert',
                       'Anand',
                       '2',
                       '2',
                       '2',
                       '2',
                       'tre'
                     ],
          'seetha' => [
                        'seetha',
                        '1',
                        '2',
                        '3',
                        '4',
                        'rew'
                      ]
        };

[download]

The data that I used are coming from Re: Multiple values for a single key (Updated), but it should work out of the box for your case also.

__DATA__

Anand,1,2,3,4,xyz
Anand,2,3,4,5,wer
Anand,3,4,4,4,ert
seetha,1,2,3,4,rew
Anand,2,2,2,2,tre

[download]

By creating a HASHES OF ARRAYS you have the ability to extract the keys and values easier.

Update: Or if you prefer to reduce it by one line more and create HASHES OF ARRAYS and use as a key the line number (for easier data retrieval) you can do it like this. Sample bellow:

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my %HoA;
while (<>) {
    chomp;
    if ( $. <= 12 ) {
    if (index($_, ',') != -1) {
        push @{ $HoA{$.} }, split(/,/, );
            $. = 0 if $. == 12; # reset line number
    }
    else {
        warn "Line could not be parsed: $_\n";
    }
    }
} continue {
    close ARGV if eof;
}

print Dumper \%HoA;

__END__

$ perl test.pl test.csv
$VAR1 = {
          '5' => [
                   'Anand',
                   '2',
                   '2',
                   '2',
                   '2',
                   'tre'
                 ],
          '1' => [
                   'Anand',
                   '1',
                   '2',
                   '3',
                   '4',
                   'xyz'
                 ],
          '3' => [
                   'Anand',
                   '3',
                   '4',
                   '4',
                   '4',
                   'ert'
                 ],
          '2' => [
                   'Anand',
                   '2',
                   '3',
                   '4',
                   '5',
                   'wer'
                 ],
          '4' => [
                   'seetha',
                   '1',
                   '2',
                   '3',
                   '4',
                   'rew'
                 ]
        };

[download]

Update2: You can reduce to minimum, just check if line contains comma (process) else skip.

my %HoA;
while (<>) {
    chomp;
    if ( $. <= 12 ) {
    next unless ( index($_, ',') != -1 ); # or remove it also
    push @{ $HoA{$.} }, split(/,/, );
        $. = 0 if $. == 12; # reset line number
    }
} continue {
    close ARGV if eof;
}

[download]

Update3: Even further:

my %HoA;
while (<>) {
    chomp;
    next unless ( index($_, ',') != -1 ); # remove if not necessary
    push @{ $HoA{$.} }, split(/,/, ) if ( $. <= 12 );
    $. = 0 if $. == 12; # reset line number
} continue {
    close ARGV if eof;
}

[download]

Update4: Line numbering reset, sorry just remembered you said you want to read every 12 lines a file with thousands of lines:

my %HoA;
while (<>) {
    chomp;
    next unless ( index($_, ',') != -1 ); # remove if not necessary
    push @{ $HoA{$.} }, split(/,/, ) if ( $. <= 12 );
    $. = 0 if $. == 12; # reset line number
} continue {
    close ARGV if eof;
}

[download]

Hope this helps, BR.

Seeking for Perl wisdom...on the process of learning...not there...yet!

Replies are listed 'Best First'.
Re^2: What can I do to improve my code - I'm a beginner (Updated)
by Anonymous Monk on Aug 11, 2017 at 08:35 UTC
    Thanks for your reply! As I say I'm a beginner so this took quite a while to digest but now I've re-read it I'm starting to understand what you are saying. Thank you for your help!
[reply]

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