Question

Given a RDF file, I want to write a python script to validate the file and comment if in wrong format. HOw do I do this with RAptor? or Sax or is there any other library? No luck with w3.

Answer 1

You have two options with raptor:

Option 1: Use the rapper command line, this is super fast. The function below is an example in python to wrap up the command. The -c option is to just count the number of triples. The parameter lang is just an option to specify the RDF format ntriples, rdfxml, turtle, … The function checks the return code and throws an exception in case anything went wrong.

def rapper_count(f,lang):
    p=subprocess.Popen(["rapper","-i",lang,"-c",f],stdout=subprocess.PIPE,stderr=subprocess.PIPE)
    output, err = p.communicate()
    ret = p.poll()
    if ret <> 0:
        raise Exception, "Error parsing with rapper\n%s"%err
    return int(err.split()[-2])

Option 2: Use the redland Python language bindings. Something like the following would work:

import RDF

test_file = "/some/file"

uri=RDF.Uri(string="file:"+test_file)

parser=RDF.Parser(name="turtle")
if parser is None:
  raise Exception("Failed to create RDF.Parser raptor")

count=0
for s in parser.parse_as_stream(uri,uri):
  count=count+1

print "Parsing added",count,"statements"

This code has been extracted from example.py, check it out and you’ll see more examples.