Re: Graphical Hierarchical Tree

[dfog]

Having done this sort of tree before, I know it is tougher to code than it first sounds. The following code prints out appoximately what you asked for in the command line, and should be fairly easily be tweaked to your needs. The hash is just there to emulate the database I don't have.

The main thing that is done is that all the replies at any given level are queried before getting their children. This allows us to check whether to make the pipes downward, or just leave whitespace. HTH Dave

#!perl 
use strict;


my @RootArticles = ("ArtA", "ArtB", "ArtC");
my %Children = (
        "ArtA" => "ArtD|ArtE|ArtF",
        "ArtE" => "ArtG|ArtH",
        "ArtC" => "ArtI|ArtJ",
        "ArtI" => "ArtK",
        "ArtK" => "ArtL",
           );
foreach (@RootArticles) {
    &Printout ("", $_);
    &getarticles("", $_);
}

sub getarticles {
    my $IndentString = shift;
        my $article = shift;
    my @Replies = ();
        foreach (split(/\|/, $Children{$article})) {
        push (@Replies, $_);
        }
    while (my $reply = pop(@Replies)) {
        &Printout($IndentString . '`---', $reply);
        my $NewIndent = (@Replies)?"|   ":"    ";
        &getarticles( $NewIndent . $IndentString, $reply);
    }
        return 1;
}

sub Printout {
    my ($IndentString, $String) = @_;
    print "$IndentString$String\n";
}

[yojimbo]

Thanks for that - it made sense after I stepped through it "the old-fashioned way", on paper :-)

[yojimbo]

More than two years since I was here :-) I had a reason to use this code again, and in going through it I found a small bug. As it stands, the code produces output like this, for a particular database app I'm writing:

86
87
`---90
|   `---91
    |   `---92
        |   `---93
`---88
    `---89
94

If you change &getarticles( $NewIndent . $IndentString, $reply); to &getarticles( $IndentString . $NewIndent, $reply); it works OK:

87
`---90
|   `---91
|       `---92
|           `---93
`---88
    `---89
94

YMMV, I've had no time to test this thoroughly.

[Sisyphus]

++nice. However, after adding the -w switch I got lots of uninitialized value warnings. They can be avoided by including an early check in the getarticles subroutine:


sub getarticles {
    my $IndentString = shift;
         my $article = shift;
    return unless $Children{$article};
    ...
}



Granted, not a big deal, but I like it better now, with strictures on.




-- Ricardo

use MacPerl;