I have a toy hierarchical structure made out of Is_a relations. Each row is read left-to-right: a 'chevy' is_a 'car'. I did this to practice/learn recursion and references and the such. My script reads from a 2 column table (12 lines of __DATA__ appended to the script) and displays the elements.

I have two display subroutines; one gives all the unique descendants of a concept, and the other prints an indented tree-structure of the whole 'terminology'. Each of them recursively pops the elements off of a hash of "immediate children" that was constructed with a split of the original table data.

My problem: Either subroutine on its own works fine, but both together do not. Only one display (either the tree or the unique list) works, and the other shows only one element. I tried building the hash anew after each of these subroutine calls, (as the program shows) but that did not help.

I enclose the code with one of the routines commented out. Entering "taxonomy" at the prompt will display the whole tree. Thanks for any help.

John 

#gives all descendents for a tree, given a root node

use strict;
use warnings;

my ($curr_string, $in, $select, %immed_child, %all_descends);

process_input();
load_hashes();
#make_display_string("$in");
#print "\n$curr_string\n";

load_hashes();
show_results();

sub process_input{
    while(1){
        print qq(enter concept name or "Q" to quit\n);
        chomp($in = <>);
        exit() if $in =~ /^\s*q\s*$/i;
        $in =~s/^\s*(\w+)\s*$/$1/;
        # still need to check if a valid concept
        print qq(enter:\n"A" for all descendents,\n"I" for immediate c
+hildren\n"P" for parents\n);
        chomp($select = <>);
        $select =~ s/^\s*([aip])\s*$/$1/i;
        last;
    }
}

# key: parent 
# val: list of immediate children
sub load_hashes{
    my ($child, $par);
    while(<DATA>){
        chomp;
        ($child, $par) = split/\t/;
        push @{$immed_child{$par}}, $child;
    }
}

#global hash needed to exchange vals w other subs
sub get_descends{
    my $root = shift;
    $all_descends{$root}++ if $root;
    while(1){
         last unless my $immed = pop @{$immed_child{$root}};
        get_descends($immed);
        $all_descends{$immed}++;
    }
    return keys %all_descends;
}

sub make_display_string{
    my $root = shift;
    my $level = shift ;
    $curr_string = shift || $root;
    #    $curr_string = "\n". $curr_string;
    $level++;
    while (1){
        last unless my $immed = pop @{$immed_child{$root}};
        $curr_string .="\n".  "\t" x $level .  $immed;
        make_display_string($immed, $level, $curr_string);
    }
    #$curr_string = "\n" . $curr_string;
}
        
sub show_results{
    $" = "\n\t"; 
    if ($select =~ m/a/i){
        print qq(\ndescendents of \n"$in":\n);
        my @descends = get_descends($in);
        print "\t@descends\n";
    } 
    elsif ($select =~m/i/i){
        if (@{$immed_child{$in}}){
            print qq(\nimmediate children of \n"$in":\n);
            print "\t@{$immed_child{$in}}\n";
        }
        else{
            print "no immediate children of $in";
        }
    }
    elsif ($select =~ m/p/i){
        print "working on this\n";
    }
}
        
        
            
__DATA__
vehicle    taxonomy
exercise device    taxonomy
computer topic    taxonomy
automobile    vehicle
ford    automobile
chevy    automobile
bike    vehicles
bike    exercise device
jumprope    exercise device
treadmill    exercise device
perl    computer topic
database    computer topic

[download]

In reply to recursive difficulty by jjohhn

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.