Given an OWL file of the RadLex ontology, extract all the class/terms preferred names into a file

extract_radlex_terms.py

from lxml import etree

radlex_tree = etree.parse('Radlex3.13.1.owl').getroot()

# Get all the term names of the Ontology, in a list.
all_terms = radlex_tree.xpath('//x:Preferred_name/text()',
                              namespaces={'x': radlex_tree.nsmap[None]})

with open('radlex_all_terms_names.txt', 'w') as f:
    for term in all_terms:
        f.write(term.encode('utf-8') + '\n')