comment on

I have an array of hashes, @Tree. One of the elements in each hash, Path is itself an array of digits. For each element in @Tree, $_->{Path} can have from one to five (at present - could be even more) elements. And I need to sort @Tree so that it's sorted first by $_->{Path}->[0], then by $_->{Path}->[1] and so on.

In case that doesn't make any sense, I've done

    for my $h (@Tree) {
        print "$_ " for @{$h->{Path}};
        print "\n";
    }
[download]

... for before and after, to show what I'm trying to achieve:

BEFORE

5 32 37
5 32 38
5 32 39
3 12 11 19 20
3 12 11 21
3 12 22
3 12 23
5 32 40
3 12 24
5 32 41
3 25
5 32 42
2 26
5 32 43
2 26 27
2 26 28
2 26 29
0 1
1 2
1 3
3 12 10
1 4
3 12 11
1 5
3 12
2 6
3 12 13
3 12 7
3 12 11 19 14
3 12 8
2 26 30
3 12 11 19 15
3 12 9
5 32 31
3 12 11 19 16
5 32
3 12 11 19 17
5 32 33
3 12 11 19 18
5 32 34
3 12 11 19
5 32 35
5 32 36
[download]

AFTER:

0 
1 2 
1 3 
1 4 
1 5 
2 6 
2 26 
2 26 27 
2 26 28 
2 26 29 
2 26 30 
3 12 
3 12 7 
3 12 8 
3 12 9 
3 12 10 
3 12 11 
3 12 11 19 
3 12 11 19 14 
3 12 11 19 15 
3 12 11 19 16 
3 12 11 19 17 
3 12 11 19 18 
3 12 11 19 20 
3 12 11 21 
3 12 13 
3 12 22 
3 12 23 
3 12 24 
3 25 
5 32 
5 32 31 
5 32 33 
5 32 34 
5 32 35 
5 32 36 
5 32 37 
5 32 38 
5 32 39 
5 32 40 
5 32 41 
5 32 42 
5 32 43
[download]

I've tried lots of different variations on

    for (5..0) {
        @Tree = sort {
        $a->{Path}->[$_] <=> $b->{Path}->[$_]
    } @Tree;
    }
[download]

... none of which worked. In the end I gave up in disgust and did

    for my $page (@Tree) {
        my $Sort = 0;
        my $M = 100;
        for (@{$page->{Path}}) {
            $Sort += $M * $_;
            $M = $M / 100;
        }
        $page->{Sort} = $Sort;
    }

    @Tree = sort {$a->{Sort} <=> $b->{Sort}} @Tree;
[download]

... which works, but is UGLY and probably slow and fattening. I'd really love to see a more elegant solution, if some monk can suggest one. Now, I got this result with the following rather clunky method:

§ George Sherston

2002-07-06 Edit by Corion: Added readmore tag

In reply to Complex Sort - using varying numbers of parameters by George_Sherston

Are you posting in the right place? Check out Where do I post X? to know for sure.
Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
<code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
Want more info? How to link or How to display code and escape characters are good places to start.


Perl Monk, Perl Meditation
	PerlMonks