On May 24, Gustho said:
>Below is a sample directory listing of the mail folder
>on a Linux box, I would like to sort the same using
>the last field (ie. lward, ohara, dray) starting with
>the 2nd character (ie from ward , hara and ray) :
>
>-rw------- 1 lward mail 0 May 24 15:43 lward
>-rw------- 1 ohara mail 8303 May 24 15:42 ohara
>-rw------- 1 dray mail 0 May 24 15:42 dray
A Schwartzian Transform (or maybe even a Guttman-Rosler Transform) seems
like a good idea here.
@sorted =
# get the original line back
map { $_->[0] }
# sort based on the string
sort { $a->[1] cmp $b->[1] }
# create [ line, string ] array references
map { [ $_, /\S(\S+)$/ ] }
# however you get the directory listing...
qx(ls -la $dir);
A GRT would require one scan through the list first, to find the longest
username.
@files = qx(ls -la $dir);
$maxlen = 0;
# loop over the usernames
for (map /\S(\S+)$/, @files) {
push @usernames, $_;
$maxlen = length if $maxlen < length;
}
Now the GRT looks like:
@sorted =
# get rid of leading sorting string
map { s/^\S+\s+// }
# sort natively -- the signature of the GRT
sort
# build the string of "prefix" . " " . $line
# padding the username properly
map { sprintf "%-${maxlen}s %s", $usernames[$_], $files[$_] }
# the indices of the array, not the actual elements
0 .. $#files;
I hope this sheds some light on an interesting problem.
--
Jeff "japhy" Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
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Perl Programmer at RiskMetrics Group, Inc. http://www.riskmetrics.com/
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** I need a publisher for my book "Learning Perl's Regular Expressions" **
