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From: arielf@tasu8c.UUCP (Ariel Faigon)
Newsgroups: comp.lang.perl
Subject: Re: How to sort on right most column
Summary: Proposed solution needs a little fix
Keywords: associative-array, unique-key
Message-ID: <5855@taux01.nsc.com>
Date: 16 May 91 10:48:13 GMT
References: <1991May15.182131.20425@uvaarpa.Virginia.EDU>
Sender: netnews@taux01.nsc.com
Reply-To: arielf@tasu8c.UUCP (Ariel Faigon)
Organization: National Semiconductor (IC) Ltd, Israel
Lines: 50

+--- In the referenced article, Barr3y Jaspan wrote:
||> I have the following data in this format - I want to sort it on the
||> right most column.
||> 
||>   0    1   2                              3                     4
||> 
||>   a    b   c                              c                     e
||> 
||>  FOO  BAR ACE CORPORATION                SUNNYVALE              2.00
||>  FOO  BAR ACER COMPUTED COMPANY          MILPITAS              20.00
|
| ... ]
|Well, since you know the sort key is the last number on each line, you
|could do something like this (untested):
|
|while (<>) {
|	/([\d.]+)$/;
|	$lines{$1} = $_;
|}
|
|for (sort numerically keys %lines) {
|	print $lines{$_};
|}
|
|sub numerically {
|	$a <=> $b;
|}
|
|The idea is to use the number at the end of a line as a key in an
|associative array, storing each entire line of text keyed on its final
|number. [more deleted ...]
+------

Barr3y's solution is of course most straight forward.
One problem remains though, since associative array keys are unique,
lines with the same key (same last column) will overwrite each other.
The solution is to concatenate lines with the same key (the '\n' is
left intact thanks to Perl). i.e. to replace the line:
>       $lines{$1} = $_;
With
	$lines{$1} .= $_;

This should do what the original poster wanted.
Peace, Ariel


Ariel Faigon
National Semiconductor Corp. (NSTA Design Center)
6 Maskit St.  P.O.B. 3007, Herzlia 46104, Israel   Tel. +972 52-522272
arielf@taux01.nsc.com