[Purdue-pm] How to sort one dimension of a 2d array

[Rick Westerman]

On Jan 29, 2010, at 9:15 AM, Phillip San Miguel wrote:

> This is probably pretty straight forward, but:
>
> I have a hash of 2d arrays. I want to sort by numerical value  
> across one of these dimensions. What would be the syntax for that?
>
> $table{$colors}[0..num_of_traces-1][0..num_data_points-1]
>
> I want sort the values in the first (traces) dimension.
>
> When I try to write the sort syntax my head starts spinning.
>
> -- 
>

I found myself floundering as well but then realized that it was  
because I was unsure what you wanted.   Also because the problem is  
difficult!

  Using an example and using %t instead of %table, let us say you have:


$t{red}[0,0]
$t{green}[2,0]
$t{blue}[1,0]
$t{blue}[4,0]
$t{red}[2,0]
$t{blue}[0,0]

Do you want the sort to look like:

$t{red}[0,0]
$t{blue}[0,0]
$t{blue}[1,0]
$t{green}[2,0]
$t{red}[2,0]
$t{blue}[4,0]

Or like:

$t{red}[0,0]
$t{red}[2,0]
$t{green}[2,0]
$t{blue}[1,0]
$t{blue}[0,0]
$t{blue}[4,0]

In others all color data jumbled together or per-color data sorted?

Assuming the latter (which makes more sense to me) then I would do  
multiple sorts so that  the sort would look like:

my %sorted;

@{$sorted{$color}} =
     sort  { $a->[0]  <=> $b->[0] } @{$table{$color}}
     foreach my $color (keys %table);


There might be a way to combine the sort into one mega-sort but that  
would hurt my brain.   Test program (with more data) is enclosed.   
Let us know if you want the data sorted in a different way.

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-- Rick