Re: [MacPerl] Sorting lines in a file

[Chris Nandor <pudge@pobox.com>]

At 19.19 -0400 1999.05.19, Scott Prince wrote:
>#!perl
>@lines = ('a\tb\tc',
>          'e\ta\tz',
>          'x\ty\ts',)
>$sortby = '2'; # or whatever field you want
>@listrefs = map { [$_, (split(/\t/, $_))[$sortby] ] } @lines;
>@newrefs  = sort { $a->[1] cmp $b->[1] } @listrefs;
>@lines     = map { $_->[0] } @newrefs;
>foreach $l (@lines) { print qq!$l\n!; }
>exit;

That uses the great Schwartzian Transform (map sort map) technique, but it
would likely be more efficient if you didn't assign to a new variable each
step.

#!perl
@lines = ("a\tb\tc",
          "e\ta\tz",
          "x\ty\ts",);  # you needed "'s instead of ''s and a semicolon above
$sortby = '2'; # or whatever field you want
@lines =  map { $_->[0] }
          sort { $a->[1] cmp $b->[1] }
          map { [$_, (split(/\t/, $_))[$sortby] ] }
          @lines;
foreach $l (@lines) { print qq!$l\n!; }
exit;

Not a huge deal, but might get some sizable wins on larger data sets, as
assigning a large list to an array can be a drag if you don't need to do it.

--
Chris Nandor          mailto:pudge@pobox.com         http://pudge.net/
%PGPKey = ('B76E72AD', [1024, '0824090B CE73CA10  1FF77F13 8180B6B6'])

===== Want to unsubscribe from this list?
===== Send mail with body "unsubscribe" to macperl-request@macperl.org