Re: 'ls -C' column style

And here's mine, which again cycles to pick the max number of columns possible. Note that both width and spacer width can be specified.

use strict;

my $width = 80;
my $spacer = 2;
my @files = sort(split(/\s+/, join('', <DATA>)));

my ($pl, $c, $i, $j, $max, $total, @max, @sorted); 

while () {
    $pl = ($#files + 1) / ++$c;
    $pl = int $pl + 1 if $pl != int $pl;
    $total = 0;
    for ($i = 0; $i < $c; $i++) {
        $max = 0; 
        for ($j = 0; $j < $pl; $j++) {
            $max = length($files[$i*$pl+$j])
                if $max < length($files[$i*$pl+$j]);
        }
        $total += $max + $spacer;
    }
    last if ($width < $total - $spacer);
}

$pl = ($#files + 1) / --$c;
$pl = int $pl + 1 if $pl != int $pl;
for ($i = 0; $i < $c; $i++) {
    $max = 0; 
    for ($j = 0; $j < $pl; $j++) {
        $sorted[$j][$i] = $files[$i*$pl+$j];
        $max = length($files[$i*$pl+$j])
            if $max < length($files[$i*$pl+$j]);
    }
    $max[$i] = $max + $spacer;
} $max[$#max] -= $spacer;

for (@sorted) {
    $c = 0;
    print sprintf('%-'.$max[$c++].'s', $_) for (@$_);
    print "\n";
}

__DATA__
B           Digest      Filter     MIME       SDBM_File  Time     util
ByteLoader  DynaLoader  GDBM_File  NDBM_File  Safe       Unicode
Cwd         Encode      I18N       ODBM_File  Socket     XS
DB_File     Errno       IO         Opcode     Storable   attrs
Data        Fcntl       IPC        POSIX      Sys        re
Devel       File        List       PerlIO     Thread     threads
[download]

Comment on Re: 'ls -C' column style Download Code

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Re^2: 'ls -C' column style by hv (Prior) on Nov 05, 2004 at 11:44 UTC
Thanks for this; given the number of ways of doing: `$pl = int $pl + 1 if $pl != int $pl;` [download] I'm looking forward (perhaps unwisely) to being able to define an infix ⌈...⌉ operator for ceiling(). In general that line isn't a safe way of getting a ceiling, since it relies on equality testing of a floating point number; in this case though it would be dangerous only if the list of items were so large as to be impractical to display so it isn't really a problem. For generality I prefer the approach taken in some of the other examples above, effectively: `sub ceildiv { my($num, $div) = @_; return int(($num + $div - 1) / $div); }` [download] .. and I suspect you avoided this only because you were using `++$c` within the expression - I'd have preferred: `++$c; $pl = int((@files + $c - 1)/$c);` [download] Note that your approach of varying only the number of columns does miss some optimal solutions; for example, with `$width = 20, $spacer = 2` you output the results in a single column even though the last 12 items could fit into a second column ('SDBM_File' being the last item that can't fit). Hugo	[reply] [d/l] [select]

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Re^2: 'ls -C' column style
by hv (Prior) on Nov 05, 2004 at 11:44 UTC

Thanks for this; given the number of ways of doing:

    $pl = int $pl + 1 if $pl != int $pl;
[download]

In general that line isn't a safe way of getting a ceiling, since it relies on equality testing of a floating point number; in this case though it would be dangerous only if the list of items were so large as to be impractical to display so it isn't really a problem. For generality I prefer the approach taken in some of the other examples above, effectively:

  sub ceildiv {
    my($num, $div) = @_;
    return int(($num + $div - 1) / $div);
  }
[download]

++$c

  ++$c;
  $pl = int((@files + $c - 1)/$c);
[download]

Note that your approach of varying only the number of columns does miss some optimal solutions; for example, with $width = 20, $spacer = 2 you output the results in a single column even though the last 12 items could fit into a second column ('SDBM_File' being the last item that can't fit).

Hugo

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