Re: recursive hash layer removal question

Oops - was decrementing twice. Thanks for the quick notice, Roy Johnson.

use strict;
use warnings;

use Data::Dumper;

my $W={
    'A' => {
        'L' => {
            'D'=>99,
            'X'=>99,
              },
        'C' =>{
            'E'=>99
             },
          }, 
    'X' => {
        'Q'=>{
            'O'=>99,
            },
        'T'=>{
            'U'=>99,
            },
          }, 
    };

remove($W, 2);
print Dumper($W);

sub remove {
    my ($p, $d) = @_;
    if ($d-- > 1) {
        remove($_, ($d)) for values %$p; # Had second decrement here
    }
    else {
        my %newhash;
        for (values %$p) {
            @newhash{keys %$_} = values %$_;
        }
        $_[0] = \%newhash;
    } 
}
[download]

Comment on Re: recursive hash layer removal question Download Code

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recursive hash layer removal question by wertert (Sexton) on May 11, 2005 at 14:01 UTC
Thanks for all your help. Lots of good stuff here. At the risk of appearing useless I may need some help with code provided by TedPride ( very cool BTW ). `sub remove { my ($p, $d) = @_; if ($d-- > 1) { remove($_, ($d)) for values %$p; # Had second decrement here } else { my %newhash; for (values %$p) { @newhash{keys %$_} = values %$_; } $_[0] = \%newhash; } }` [download] I've not seen one of these before. It's an hash but it looks like an array ie '@' `for (values %$p) { @newhash{keys %$_} = values %$_; } $_[0] = \%newhash;` [download] What is going on here then ? Checked out my cookbook etc but can't find a reference to this syntax. One other slight complication is the data can actually look like this; `$W={ 'A' => { 'L' => { 'D'=>99, 'X'=>99, }, 'C' =>{ 'E'=>99 }, }, 'X' => { 'Q'=>{ 'O'=>99, }, 'T'=>{ 'U'=>99, }, }, 'W' => 99, };` [download] Now when we collapse level 2 ie LCQT I don't want to change the value for 'W'. So only drop values on the target level if they are HASH. So really it's a mix of H,HOH and HOHOH etc. Thanks again for your help. Jeff	[reply] [d/l] [select]
Re: recursive hash layer removal question by Transient (Hermit) on May 11, 2005 at 14:24 UTC
It's a hash slice assignment (in other words, it's not a hash, it is an array). Basically you're saying, here is a list of keys and for each of these keys assign these values (since 'keys' and 'values' return lists). I can't find any particular documentation on it, but it does work :)	[reply]