I came across this solution
as I'm trying to convert code presented here. Code is also provided at the end of this question
but I cannot make any headway in using the package 2to3. I've tried using the technical guide here but to no avail.
I'm ready to be spoonfed, if someone is willing to assist. I've used the commandline to run the code so far and I'm not sure why I keep getting the error
2to3 Amended.py
Where Amended.py is the file that has 2.x version code. I get
SyntaxError: invalid syntax
as an error
import csv
class SimpleGraph:
def __init__(self):
self._spo = {}
self._pos = {}
self._osp = {}
def add(self,sub_pred_obj):
"""
Adds a triple to the graph.
"""
self._addToIndex(self._spo, sub, pred, obj)
self._addToIndex(self._pos, pred, obj, sub)
self._addToIndex(self._osp, obj, sub, pred)
def _addToIndex(self, index, a, b, c):
"""
Adds a triple to a specified index.
"""
if a not in index: index[a] = {b:set([c])}
else:
if b not in index[a]: index[a][b] = set([c])
else: index[a][b].add(c)
def remove(self, (sub, pred, obj)):
"""
Remove a triple pattern from the graph.
"""
triples = list(self.triples((sub, pred, obj)))
for (delSub, delPred, delObj) in triples:
self._removeFromIndex(self._spo, delSub, delPred, delObj)
self._removeFromIndex(self._pos, delPred, delObj, delSub)
self._removeFromIndex(self._osp, delObj, delSub, delPred)
def _removeFromIndex(self, index, a, b, c):
"""
Removes a triple from an index and clears up empty indermediate structures.
"""
try:
bs = index[a]
cset = bs[b]
cset.remove(c)
if len(cset) == 0: del bs[b]
if len(bs) == 0: del index[a]
# KeyErrors occur if a term was missing, which means that it wasn't a valid delete:
except KeyError:
pass
def triples(self, (sub, pred, obj)):
"""
Generator over the triple store.
Returns triples that match the given triple pattern.
"""
# check which terms are present in order to use the correct index:
try:
if sub != None:
if pred != None:
# sub pred obj
if obj != None:
if obj in self._spo[sub][pred]: yield (sub, pred, obj)
# sub pred None
else:
for retObj in self._spo[sub][pred]: yield (sub, pred, retObj)
else:
# sub None obj
if obj != None:
for retPred in self._osp[obj][sub]: yield (sub, retPred, obj)
# sub None None
else:
for retPred, objSet in self._spo[sub].items():
for retObj in objSet:
yield (sub, retPred, retObj)
else:
if pred != None:
# None pred obj
if obj != None:
for retSub in self._pos[pred][obj]:
yield (retSub, pred, obj)
# None pred None
else:
for retObj, subSet in self._pos[pred].items():
for retSub in subSet:
yield (retSub, pred, retObj)
else:
# None None obj
if obj != None:
for retSub, predSet in self._osp[obj].items():
for retPred in predSet:
yield (retSub, retPred, obj)
# None None None
else:
for retSub, predSet in self._spo.items():
for retPred, objSet in predSet.items():
for retObj in objSet:
yield (retSub, retPred, retObj)
# KeyErrors occur if a query term wasn't in the index, so we yield nothing:
except KeyError:
pass
def value(self, sub=None, pred=None, obj=None):
for retSub, retPred, retObj in self.triples((sub, pred, obj)):
if sub is None: return retSub
if pred is None: return retPred
if obj is None: return retObj
break
return None
def load(self, filename):
f = open(filename, "rb")
reader = csv.reader(f)
for sub, pred, obj in reader:
sub = unicode(sub, "UTF-8")
pred = unicode(pred, "UTF-8")
obj = unicode(obj, "UTF-8")
self.add((sub, pred, obj))
f.close()
def save(self, filename):
f = open(filename, "wb")
writer = csv.writer(f)
for sub, pred, obj in self.triples((None, None, None)):
writer.writerow([sub.encode("UTF-8"), pred.encode("UTF-8"), obj.encode("UTF-8")])
f.close()
if __name__ == "__main__":
g = SimpleGraph()
g.add(("blade_runner", "name", "Blade Runner"))
g.add(("blade_runner", "name", "Blade Runner"))
g.add(("blade_runner", "release_date", "June 25, 1982"))
g.add(("blade_runner", "directed_by", "Ridley Scott"))
print list(g.triples((None, None, None)))
print list(g.triples(("blade_runner", None, None)))
print list(g.triples(("blade_runner", "name", None)))
print list(g.triples(("blade_runner", "name", "Blade Runner")))
print list(g.triples(("blade_runner", None, "Blade Runner")))
print list(g.triples((None, "name", "Blade Runner")))
print list(g.triples((None, None, "Blade Runner")))
print list(g.triples(("foo", "name", "Blade Runner")))
print list(g.triples(("blade_runner", "foo", "Blade Runner")))
print list(g.triples(("blade_runner", "name", "foo")))
