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Re: Graphical Hierarchical Tree

by dfog (Scribe)
on Mar 05, 2001 at 00:19 UTC ( #62124=note: print w/ replies, xml ) Need Help??

in reply to 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"; }

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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 :-)
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
    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.
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;

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