Hello

Today I needed to turn values in a csv into a chunk of XML (required for an XLST transformation). Because the data in the XML is nested severa layers deep, the csv header describes the location in the XML like a file directory

#id   layer/first   layer/second
id1   value1         value2
id2   value3         value4

[download]

The only way I could work out how to build a branch and attach a leaf in a hash was the following. From there I can use XML::Simple to generate the XML. If there was an easier way I would love to know it


#!/usr/bin/perl -w

use strict;
use Data::Dumper;

my $list1 = "this/is/a/twig";
my $list2 = "this/is/a/branch";
my $list3 = "this/is/another/branch";

my $hash = {};
my $hashroot = $hash;
my @hashtags1 = split(/\//, $list1);
my @hashtags2 = split(/\//, $list2);
my @hashtags3 = split(/\//, $list3);

attach_leaf($hash,\@hashtags1, "leaf1");
attach_leaf($hash,\@hashtags2, "leaf2");
attach_leaf($hash,\@hashtags3, "leaf3");

print Dumper($hashroot);

sub attach_leaf{
    my ($tree, $branch, $leaf) = @_;

    # Work along the branch
    for(my $i = 0; $i < scalar(@$branch); $i++) { 
        # build branch
        if($i != (scalar(@$branch) - 1)){
            # build new branch if it doesn't exist already
            $tree->{$$branch[$i]} = {} if(! exists $tree->{$$branch[$i
+]}); 
            $tree = $tree->{$$branch[$i]};
        }
        # attach leaf
        else{
            $tree->{$$branch[$i]} = $leaf;
            return $hash;
        }
    }
}

[download]
output was 

$VAR1 = {
          'this' => {
                      'is' => {
                                'a' => {
                                         'branch' => 'leaf2',
                                         'twig' => 'leaf1'
                                       },
                                'another' => {
                                               'branch' => 'leaf3'
                                             }
                              }
                    }
        };

[download]

In reply to Building a tree 1 leaf at a time by markdibley

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