Re: How to Save a variable outside of a loop

You also need to skip the comparison for the first line of data.

#!/usr/bin/perl
use warnings;
use strict;
my $prev_l;
my $prev_p;
my $count = 0; ### add
while(<>){
  my $hitlength;
  my $prevalence;
 
  my $line = $_;  
  chomp $line;
  if ($line =~ /^[\d]/){
    my @hitline = split(/,/ , $line);
    $hitlength  = $hitline[4];
    $prevalence = $hitline[65];
    if( ($count++) and
        ($hitlength  == $prev_l) and
        ($prevalence == $prev_p) ){
        next;
    } else {
      print "$line\n";    
    }
    $prev_l = $hitlength;
    $prev_p = $prevalence;
  } 
}
[download]

poj

Comment on Re: How to Save a variable outside of a loop Download Code

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Re^2: How to Save a variable outside of a loop by Laurent_R (Canon) on Aug 01, 2015 at 10:16 UTC
You also need to skip the comparison for the first line of data. Or you could just give an initial dummy value to the two previous variables, thereby saving some steps within the loop: `#!/usr/bin/perl use warnings; use strict; my ($prev_l, $prev_p) = ("", ""); while(<>){ my $hitlength; my $prevalence; my $line = $_; chomp $line; if ($line =~ /^[\d]/){ my @hitline = split(/,/ , $line); $hitlength = $hitline[4]; $prevalence = $hitline[65]; if( $hitlength == $prev_l and $prevalence == $prev_p ){ next; } else { print "$line\n"; } $prev_l = $hitlength; $prev_p = $prevalence; } }` [download]	[reply] [d/l]
Re^3: How to Save a variable outside of a loop by AnomalousMonk (Archbishop) on Aug 01, 2015 at 10:38 UTC
That'll yield a warning: `c:\@Work\Perl\monks>perl -wMstrict -le "my $x = ''; print 'equal' if $x == 1; " Argument "" isn't numeric in numeric eq (==) at -e line 1.` [download] Give a man a fish: `<%-(-(-(-<`	[reply] [d/l] [select]
Re^4: How to Save a variable outside of a loop by Laurent_R (Canon) on Aug 01, 2015 at 12:18 UTC
Yes, AnomalousMonk, you're right, I did not pay attention to the fact that the code is using numeric comparison. I'm doing this type of things regularly, but usually with the string `eq` operator, even when the data string is numeric (say a customer number or a phone number with only digits). Reducing the number of operations made in the `while (<$fh>)` loop makes some sense when removing duplicates from a 500-million-line file.	[reply] [d/l] [select]
Re^3: How to Save a variable outside of a loop by poj (Abbot) on Aug 01, 2015 at 10:48 UTC
Apart from the warning, you have to be certain that on the first line of data those 2 fields don't contain the dummy values you initialize to otherwise it will be treated as a duplicate and skipped. poj	[reply]