Re^2: representing a tree

you're right it does sound's like homework but is has passed quite some time since i last attended any real classes. so what i tried so far is through recursion catch the pattern to transform it to the nice tree :

use strict;

open (T, "<", "file.txt")|| die "$!";
open (OUT, ">", "out.txt") || die "$!";
my $t = $ARGV[0];# $t could be 3 not 1 so that i can start from that p
+oint
my %hash;

while (<T>){
    m/^(\d+?),(\d+?)\n/g;
    my ($child, $parent) = ($2,$1);
    push @{$hash{$child}},$parent;
        }


walk($t);

sub walk {
          my $numb = shift;
             print OUT "\|->$numb\n";
             #my @walk = $numb; 
          for (@{$hash{$numb}}){
                  #push @walk, 
                  #print OUTNOD "\|->>>";
                  walk($_);
                  print OUTNOD "\|->>";
          }
         #return @walk; 
}
[download]

there are some relict's in the code but that is because i'm still trying to figure it out.

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Re^3: representing a tree by moritz (Cardinal) on Jul 03, 2008 at 10:28 UTC
`push @{$hash{$child}},$parent;` That doesn't look right. Usually you store a tree the other way round, i.e. for each node you store a list of child nodes. So change that to `push @{$hash{$parent}}, $child;`, and you'll start to get some results. This is how I'd traverse the tree: `sub other_walk { my ($indent, $item) = @_; print ' ' x (2 * $indent); print $item, "\n"; for (@{$hash{$item}}){ other_walk($indent+1, $_); } } other_walk(0, 1);` [download] It's not perfect, but I think it goes into the right direction, and you can add your ASCII art eye candy later on ;-)	[reply] [d/l] [select]

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Re^3: representing a tree
by moritz (Cardinal) on Jul 03, 2008 at 10:28 UTC

push @{$hash{$child}},$parent;

That doesn't look right. Usually you store a tree the other way round, i.e. for each node you store a list of child nodes. So change that to push @{$hash{$parent}}, $child;, and you'll start to get some results.

This is how I'd traverse the tree:

sub other_walk {
    my ($indent, $item) = @_;
    print ' ' x (2 * $indent);
    print $item, "\n";
    for (@{$hash{$item}}){
        other_walk($indent+1, $_);
    }
}

other_walk(0, 1);
[download]

It's not perfect, but I think it goes into the right direction, and you can add your ASCII art eye candy later on ;-)

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