## Multiple Dimension Array with multiple sort

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• This may be a simple question, but I have searched for this answer. Suppose I have a multi-di array. I can make it sort by any one element. But what I need
Message 1 of 12 , Apr 7, 2011
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This may be a simple question, but I have searched for this answer.
Suppose I have a multi-di array. I can make it sort by any one element. But what I need to sort by two? In my simple example below, what if I wanted to sort by the animal name, and then by number of legs? I am grateful for any help or tips on this.

#!/usr/local/bin/perl
use strict;
use warnings;

my @critters; #multi-di with animal name and number of legs
\$critters[0][0] = "dog";
\$critters[0][1] = "4";
\$critters[1][0] = "cat";
\$critters[1][1] = "4";
\$critters[2][0] = "monkey";
\$critters[2][1] = "2";

#I know I can sort by any one field with
@critters = sort { \$a->[0] cmp \$b->[0] } @critters;
my \$critterCount= @critters;
for (my \$count=0;\$count<\$critterCount;\$count++) {
print "The critter \$critters[\$count][0] has \$critters[\$count][1] legs\n";
}
• ... Tim Suppose I have a multi-di array. I can make it sort by any one Tim element. But what I need to sort by two? In my simple example Tim below, what
Message 2 of 12 , Apr 7, 2011
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>>>>> "Tim" == Tim Lewis <twlewis@...> writes:

Tim> Suppose I have a multi-di array. I can make it sort by any one
Tim> element. But what I need to sort by two? In my simple example
Tim> below, what if I wanted to sort by the animal name, and then by
Tim> number of legs? I am grateful for any help or tips on this.

Since that can be interpreted two ways, I'm going to pretend you
actually said "with the major sort by animal name, using the number of
legs to break ties as a secondary sort".

Tim> my @critters; #multi-di with animal name and number of legs
Tim> \$critters[0][0] = "dog";
Tim> \$critters[0][1] = "4";
Tim> \$critters[1][0] = "cat";
Tim> \$critters[1][1] = "4";
Tim> \$critters[2][0] = "monkey";
Tim> \$critters[2][1] = "2";

my @sorted = sort {
\$a->[0] cmp \$b->[0]
or \$a->[1] <=> \$b->[1];
} @critters;

This is covered in the Alpaca book.

And now, for the traditional "don't post here" comment:

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*
* The official one is at beginners@..., with instructions on how to
* join at http://lists.perl.org/list/beginners.html.
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--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
<merlyn@...> <URL:http://www.stonehenge.com/merlyn/>
Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
See http://methodsandmessages.posterous.com/ for Smalltalk discussion
• Thanks Randall. I was close. I was using cmp instead of for the number portion. Thanks again. I did not know about the other listserver, and found this
Message 3 of 12 , Apr 7, 2011
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Thanks Randall. I was close. I was using "cmp" instead of <=> for the number portion.

Thanks again.
I did not know about the other listserver, and found this one on Yahoo. I will check out the other one.

Tim

---- merlyn@... wrote:
> >>>>> "Tim" == Tim Lewis <twlewis@...> writes:
>
> Tim> Suppose I have a multi-di array. I can make it sort by any one
> Tim> element. But what I need to sort by two? In my simple example
> Tim> below, what if I wanted to sort by the animal name, and then by
> Tim> number of legs? I am grateful for any help or tips on this.
>
> Since that can be interpreted two ways, I'm going to pretend you
> actually said "with the major sort by animal name, using the number of
> legs to break ties as a secondary sort".
>
> Tim> my @critters; #multi-di with animal name and number of legs
> Tim> \$critters[0][0] = "dog";
> Tim> \$critters[0][1] = "4";
> Tim> \$critters[1][0] = "cat";
> Tim> \$critters[1][1] = "4";
> Tim> \$critters[2][0] = "monkey";
> Tim> \$critters[2][1] = "2";
>
> my @sorted = sort {
> \$a->[0] cmp \$b->[0]
> or \$a->[1] <=> \$b->[1];
> } @critters;
>
> This is covered in the Alpaca book.
>
> And now, for the traditional "don't post here" comment:
>
> **************************************************
> *
> * THIS IS NOT THE OFFICIAL perl BEGINNERS GROUP.
> *
> * The official one is at beginners@..., with instructions on how to
> * join at http://lists.perl.org/list/beginners.html.
> *
> * You'll get far better response there, not to say you won't get *any* here.
> *
> **************************************************
>
>
> --
> Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
> <merlyn@...> <URL:http://www.stonehenge.com/merlyn/>
> Smalltalk/Perl/Unix consulting, Technical writing, Comedy, etc. etc.
> See http://methodsandmessages.posterous.com/ for Smalltalk discussion
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