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EASR / ONTO-PERL-1.40 / doc / example09.html 
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<title>Building an ontology from an existing sub-ontology</title>
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<h2>Working with sub-ontologies</h2>
	
<ol>
	<li><a href="#1">Building an ontology from an existing sub-ontology.</a></li>

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	<ol>
	<li> <b><a href="#1">Building an ontology from an existing sub-ontology:</a></b>
		<pre>
		
			use OBO::Parser::OBOParser;
			
			my $my_parser = OBO::Parser::OBOParser->new();
			my $onto = $my_parser->work("gene_ontology.obo");        # load: gene_ontology.obo
			
			my $sub_ontology_root_id = "GO:0007126";                 # term: meiosis
			my $term = $onto->get_term_by_id($sub_ontology_root_id); # get the term 'meiosis'
			my @descendents = @{$onto->get_descendent_terms($term)}; # get its descendants
			unshift @descendents, $term;
			
			my $term_set = OBO::Util::TermSet->new();
			$term_set->add_all(@descendents);                        # collect the descendants
			my $so = $onto->subontology_by_terms($term_set);         # get the sub-ontology
			$so->default_namespace("meiosis_ontology");
			$so->subsets($onto->subsets()->get_set());
			$so->remarks("A Meiosis Sub-Ontology");

		</pre>
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