Re: [MacPerl] Sorting lines in a file

[Scott Prince <saprince@earthlink.net>]

on 5/19/99 2:52 PM, JDE wrote...
>I'm a [Mac]Perl novice, and I have reached the end of my rope with a
>problem that I hope has a simple solution:
>
>I've created a text file in which each line is a tab delimited string/list
>recording information about a round of golf.  All I want to do is sort
>these lines by the various "elements" in each string/list, say by name, or
>course, or date, or whatever.

#!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;

See Tom Christianson's FMTETYWTK about sorting.


Scott


>
>Simplified example line:
>
>name<tab>date<tab>course<tab>tee_position<tab>score<tab>adjusted_score\n
>
>When I read the file into an array, "@allLines", I have no trouble sorting
>the array by the first element, but I am completely stumped in my efforts
>to sort the lines of the array by the other "elements" in the line.
>
>I think I know that each line is just a string, with one element, and so
>I've tried everything I can think of to break out the "sub-elements" in
>each line, none of which works:
>
>##my umpteenth, and most enterprising attempt
>##  - using what I thought was a sort function call:
>####
>sub extractElement	{
>	$oneLine = shift(@_);
>	@oneLineAsList = split(/\t/,$oneLine);
>	$chosenElement = $oneLineAsList[2];
>	return $chosenElement;
>}
>@sortedOrder = sort { &extractElement($a) cmp &extractElement($b) } 
>@allLines;
>####
>
>This method accomplishes nothing  ... both @allLines and @sortedOrder have
>the same contents, in the same order.  Consistent with this do-nothing
>result, after the sub &extractElement has done its thing, both $oneLine and
>$chosenElement are empty.   There seems to be no doubt that I am going
>about this the wrong way.
>
>I won't burden this message with the numerous other methods and workarounds
>I've attempted, since none of those worked either, and I'm holding out hope
>that there is a simple/obvious/trivial solution that one of Mac-friendly
>list gurus will point out without too much opprobrium.
>
>In any event, thanks for any help, and also thanks after the fact for all
>of the other helpful information I've gleaned from this list.
>
>John Echols
><defender@pianosa.com>
><www.pianosa.com>

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