Re: Graphical Hierarchical Tree

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";
}
[download]

Comment on Re: Graphical Hierarchical Tree Download Code

Replies are listed 'Best First'.
Thanks by yojimbo (Monk) on Mar 05, 2001 at 02:14 UTC
Thanks for that - it made sense after I stepped through it "the old-fashioned way", on paper :-)	[reply]
Re: Re: Graphical Hierarchical Tree by yojimbo (Monk) on Mar 11, 2003 at 17:17 UTC
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 [download] If you change `&getarticles( $NewIndent . $IndentString, $reply);` to `&getarticles( $IndentString . $NewIndent, $reply);` it works OK: 87 `---90 \| `---91 \| `---92 \| `---93 `---88 `---89 94 [download] YMMV, I've had no time to test this thoroughly.	[reply] [d/l] [select]
Re: Re: Graphical Hierarchical Tree by Sisyphus (Chaplain) on Mar 12, 2003 at 03:58 UTC
++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;	[reply]