Sorting a list of filenames

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

I am trying to sort a list of filenames, then pull the first part of the name (a date YYYYMMDD) and compare with today's date and write that file into a new if the date in the name is on or before today, am I on the right track?

@sortedbus = sort {$b <=> $a} (@busdir);

foreach $bus (@sortedbus) {

    @splbus = map {split (/_/, $bus, 1)} @sortedbus;
    
    if ($today >= @splbus[0]) {

        for ($i=0; $i++;) {

            $pers = @buschecked[i];

        } # End for loop to populate the sorted, checked array
    } # End if statement to check the current date against the Begin d
+ates
} # End foreach loop to pull each name from the sorted array, check th
+e begin date and populate the final array
[download]

Comment on Sorting a list of filenames Download Code

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Re: Could someone take a look at this code snippet? by Masem (Monsignor) on May 10, 2001 at 20:31 UTC
It might be easier to take out what you don't need with a grep: `@to_be_written = grep { split(/_/)[0] <= $today } @busdir;` [download] ... after which, you just need to take each file in @to_be_written and do what you need to do with it. Alternative, it's probably more efficient to use a foreach loop, as to only process the list once for both the requirement on being less than $today, and for the file operations: `foreach (@to_be_written) { if ( split(/_/)[0] <= $today ) { do_magic_file_copy_thing_here( $_ ); # $_ is the filename of int +erest } }` [download] Dr. Michael K. Neylon - mneylon-pm@masemware.com \|\| "You've left the lens cap of your mind on again, Pinky" - The Brain	[reply] [d/l] [select]
Re: Could someone take a look at this code snippet? by stephen (Priest) on May 10, 2001 at 20:33 UTC
At first glance, at least, it seems that your code is going to loop forever: `# Loops forever for ($i=0; $i++;) { $pers = @buschecked[i]; }` [download] I'd suggest iterating over the list itself: `# Goes through list for (@buschecked) { $pers = $_; }` [download] Plus, assigning to $pers doesn't actually do anything, so I'm not sure why you're doing it. :) May I suggest the File::Find module, plus Time::Local or one of the many other Time or Date modules on CPAN. Update: Changed Date::ParseDate to Time::Local, since it seemed more applicable. stephen	[reply] [d/l] [select]
Re: Could someone take a look at this code snippet? by thpfft (Chaplain) on May 10, 2001 at 20:41 UTC
I confess to being confused by the use of map here and scared by the apparently endless loop, which probably means i haven't understood something. Here's how i would do the main bit, anyway: `for (@sortedbus) { push (@oldbus,$_) if (m/^(\d)+?/ && make_nasty_date($1) < $today); }` [download] Which should give you a sorted list of the right files in `@oldbus`. make_nasty_date is standing for whatever mechanism you're using to convert yyyymmdd into seconds-since-epoch, assuming that's what you're doing. ps. i expect there are a hundred things wrong with the regex, so let's say it's assuming filenames in the right format.	[reply] [d/l] [select]
Re: Could someone take a look at this code snippet? by little (Curate) on May 11, 2001 at 16:08 UTC
I feel you are mixing up arrays, slices and scalars a bit. This is a slice and not an array element: @buscheckedi However: `foreach $bus (reverse sort @busdir) { $splbus = split (/_/, $bus, 1); if ($today >= $splbus) { $buschecked++; } }` [download] assuming I got what you wanted to do. But as it looks now it might then be easier to use the Schwartzian Transform. Have a nice day All decision is left to your taste	[reply] [d/l]