Using variables to create N triples in python

Question

I am currently trying to use variables to create a graph of N triples, I am not having any trouble assigning the variables, but i keep getting an error message. Here is the code:

from rdflib import Namespace, URIRef, Graph
from StringIO import StringIO


xmlns = "http://www.example.org/lexicon#"
rdf = "http://www.w3.org/1999/02/22-rdf-syntax-ns#"
lemon = "http://www.monnetproject.eu/lemon#"
graph = Graph()
F = open("new_2.txt", "r")
for line in F:

This is the part where I assign the variables. This is pretty long and I know it works so I wont include this. This following code is still part of the for line in F:

line1 = ''+synset_offset+'\rdf.lex_filenum\ '+lex_filenum+''
    line2 = ''+synset_offset+'\lemon.ss_type\ '+ss_type+''
    line3 = ''
    for item in word: 
        line3 +=''+synset_offset+'\lemon.lexical_entry\ '+iw.next()+'/n'
    line4 = ''+synset_offset+'\lemon.gloss\ '+gloss+''
    line5 = ''
    line6 = ''
    line7 = ''
    for item in S:
        pointer = ip.next()
        pos = iss.next()
        source_target = ist.next()
        line5 += ''+synset_offset+'\lemon.has_ptr\ '+pointer+'/n'
        line6 += ''+pointer+'\lemon.pos\ '+pos+'/n'
        line7 += ''+pointer+'\lemon.source_target\ '+source_target+'/n'

    contents = '''\
    '''+line1+'''
    '''+line2+'''
    '''+line3+'''
    '''+line4+'''
    '''+line5+'''
    '''+line6+'''
    '''+line7+''''''  
    tabfile = StringIO(contents)
    for line in tabfile:
        triple = line.split()                # triple is now a list of 3 strings
        triple = (URIRef(t) for t in triple) # we have to wrap them in URIRef
        graph.add(triple)

print graph.serialize(format='nt')  

This is the other code i have that prints everything correctly, showing that it is not the variables that are not working.

print('''<http://example.org/#'''+synset_offset+'''> <http://www.monnetproject.eu/lemon#lex_filenum> "'''+lex_filenum+'''".
<http://example.org/#'''+synset_offset+'''> <http://www.monnetproject.eu/lemon#ss_type> "'''+ss_type+'''".
<http://example.org/#'''+synset_offset+'''> <http://www.monnetproject.eu/lemon#gloss> "'''+gloss+'''".''')
    for item in word:
        print('''<http://example.org/#'''+synset_offset+'''> <http://www.monnetproject.eu/lemon#lex_entry> "'''+iw.next()+'''".''')

    for item in S:
        pointer = ip.next()
        pos = iss.next()
        source_target = ist.next()
        print('''<http://example.org/#'''+synset_offset+'''> <http://www.monnetproject.eu/lemon#has_ptr> "'''+pointer+'''".
<http://example.org/#'''+pointer+'''> <http://www.monnetproject.eu/lemon#pos> "'''+pos+'''".
<http://example.org/#'''+pointer+'''> <http://www.monnetproject.eu/lemon#source_target> "'''+source_target+'''".''')
    print('''\n''')

Any better ideas than the way I have it done here would be very welcome

EDIT: Now i am getting this error:

graph.add(triple)
  File "/usr/lib/python2.7/site-packages/rdflib-4.1_dev-py2.7.egg/rdflib/graph.py", line 352, in add
    def add(self, (s, p, o)):
ValueError: need more than 2 values to unpack

Answer 1

You try to concatenate a "method" with a str, which means iw.next is the "pointer" to the method and iw.next() would be its return value, which is what you want.

Being explicit:

line3 +=''+synset_offset+'\lemon.lexical_entry\ '+iw.next()+'/n'

Update (regarding the next error):

triple has to be a tuple with 3 elements, just like the function signature says:

add(self, (s, p, o))

Ignore self, since you're calling the instance method.

I'm pretty sure that triple has another type, so check that out (the easiest way is print triple in the for statement).