Build a list of files that are NOT in a list

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

So, I have a big directory full of images. The naming pattern is <Number>.<Counter>.jpg (where counter is 000, 001, 002...). I have a list of numbers which match up with Numbers that I want to keep (so for a given Number in the list, keep Number.000.jpg, Number.001.jpg, etc).

As far as I can tell, the following code should work, but the numbers it reports don't match up. Any idea what's going on?

The current output is:

33600 images in photos (8321 unique). 6571 numbers in numbers_only.txt. 5999 numbers slated for deletion.

#!/usr/bin/perl -w

use strict;

my $num_file = "numbers_only.txt";

my %currentlist;
my $i = 0;
open(CURRFILE, "<$num_file") or die "couldn't open the num file: $!\n"
+;
while (<CURRFILE>) {
  chomp;
  $currentlist{$_}++;
  $i++;
}
close CURRFILE;

my $dir = "images/photos";

opendir FILEDIR, $dir or die "Couldn't open $dir: $!\n";
my @filelist = grep !/^\.\.?$/, readdir FILEDIR;
closedir FILEDIR;

my %uniquelist;
my %deletelist;
my $h = 0;
foreach my $pic (@filelist) {
  next unless ($pic =~ /jpg$/);
  $pic =~ s/^(\d+).*/$1/;
  $h++;
  $uniquelist{$pic}++;
  next if ($currentlist{$pic});
  $deletelist{$pic}++;

}

my $output = "delete_list.txt";

open OUT, ">$output" or die "Couldn't open output: $!\n";
my $j = 0;
foreach my $del (sort keys %deletelist) {
  print OUT "$del\n";
  $j++;
}
close OUT;

my $k = 0 + keys %uniquelist;
print "$h images in photos ($k unique). $i numbers in numbers_only.txt
+.  $j numbers slated for deletion.\n";
exit;
[download]

Comment on Build a list of files that are NOT in a list Download Code

Replies are listed 'Best First'.
Re: Build a list of files that are NOT in a list by dws (Chancellor) on Jul 03, 2002 at 19:22 UTC
In a big directory, it's easy to miss that a malformed filename has slipped in. Were this my code, I'd be more defensive about `$pic =~ s/^(\d+).*/$1/; $h++; $uniquelist{$pic}++; next if ($currentlist{$pic}); $deletelist{$pic}++;` [download] and would test whether the regexp actually matched before doing the bookkeeping.	[reply] [d/l]
Re: Build a list of files that are NOT in a list by stajich (Chaplain) on Jul 03, 2002 at 20:00 UTC
Are you sure you want to do `/^(\d+).*/` [download] If I understand your name construction properly you expected NNNN.NNNN.jpg I would write the code slightly more carefully (your 1st foreach loop) note the `\.` `my %uniquelist; my %deletelist; my $h = 0; foreach my $pic (@filelist) { next unless ($pic =~ /\.jpg$/); if( $pic =~ /^(\d+)\.(\d+)/) { my ($num,$counter) = ( $1,$2); $h++; $uniquelist{$num}++; next if ($currentlist{$num}); $deletelist{$pic}++; } else { print STDERR "saw a photo file ($pic) that did not match the expect +ed naming pattern!\n"; } }` [download] Code suggestion, you might want to replace `my $k = 0 + keys %uniquelist;` with `my $k = scalar keys %uniquelist;`, as some may feel this is more explicit.	[reply] [d/l] [select]