class EarlyFusionScorer(FusionScorer):
def __init__(self,
index_name,
association_file,
object_length_file,
assoc_mode,
retr_params,
field="content",
run_id="fusion"):
"""
:param index_name: name of index
:param association_file: document-object association file
:param object_length_file: object length file
:param assoc_mode: document-object weight mode, uniform or binary
:param retr_params: BM25 parameter dict
:param field: field to be searched
"""
self._index_name = index_name
self._elastic = Elastic(self._index_name)
self._k1 = retr_params.get("k1", 1.2)
self._b = retr_params.get("b", 0.75)
self._field = field
self._o_l = object_length(object_length_file)
self._collection_length = self._elastic.coll_length(self._field)
self._N = self._elastic.num_docs()
self._assoc_mode = assoc_mode
self.association_file = association_file
self.assoc_doc = {}
self.assoc_obj = {}
self.run_id = run_id
def score_query(self, query):
"""
Scores a given query.
:param query: query to be searched
:return: pqo
"""
aquery = self._elastic.analyze_query(query)
pr = self._elastic.search(aquery, self._field)
avg_ol = self._collection_length / (len(self.assoc_obj))
q = self.parse(aquery)
# Scoring objects, i.e., computing P(q|o)
pqo = {}
qt = Counter(q)
for t, ftq in qt.items():
# Scores each query term and sums up, i.e., computing P(t|o)
# Retrieving documents and gets IDF
n = len(self._elastic.search(
t, self._field)) # number of documents containing term t
if n == 0:
continue
idf = math.log((self._N - n + 0.5) / (n + 0.5))
# Fuses f(t,o) for each object
term = stemmer.stemWords(t.split())[0]
ftd_fused = {}
for item in pr.keys():
doc_id = item
if doc_id in self.assoc_doc:
try:
ftd = self._elastic.term_freq(doc_id, term,
self._field)
except: # doc without content
ftd = 0
for object_id in self.assoc_doc[doc_id]:
if self._assoc_mode == FusionScorer.ASSOC_MODE_BINARY:
w_do = 1
elif self._assoc_mode == FusionScorer.ASSOC_MODE_UNIFORM:
w_do = 1 / len(self.assoc_obj[object_id])
else:
w_do = 0 # this should never happen
ftd_fused[object_id] = ftd_fused.get(object_id,
0) + ftd * w_do
# Add pto into pqo
for object_id in self.assoc_obj.keys():
ol = int(self._o_l[object_id])
fftd = ftd_fused.get(object_id, 0)
score = (fftd * (self._k1 + 1)) / (
fftd + self._k1 * (1 - self._b + self._b * ol / avg_ol))
pqo[object_id] = pqo.get(object_id, 0) + idf * score
return RetrievalResults(pqo)
class EarlyFusionScorer(FusionScorer):
def __init__(self, index_name, association_file, assoc_mode, retr_params, run_id="fusion", field="content",
num=100):
"""
:param index_name: name of index
:param association_file: document-object association file
:param assoc_mode: document-object weight mode, uniform or binary
:param lambda: smoothing parameter
:param field: field to be searched
"""
self._index_name = index_name
self._elastic = Elastic(self._index_name)
self._lambda = retr_params.get("lambda", 0.1)
self._field = field
self._collection_length = self._elastic.coll_length(self._field)
self._assoc_mode = assoc_mode
self._num = num
self.association_file = association_file
self.assoc_doc = {}
self.assoc_obj = {}
self.run_id = run_id
def score_query(self, query):
"""
Scores a given query.
:param query: query to be searched
:return: pqo
"""
# retrieving documents
aquery = self._elastic.analyze_query(query)
pr = self._elastic.search(aquery, self._field, num=self._num)
q = self.parse(aquery)
# scoring objects, i.e., computing P(q|o)
pqo = {}
qt = Counter(q)
for t, ftq in qt.items():
# Scores each query term and sums up, i.e., computing P(t|o)
# Gets term frequency in collections
term = stemmer.stemWords(t.split())[0]
try:
ftc = self._elastic.coll_term_freq(term, self._field)
if ftc == None:
print("Ignore term", t)
continue
except:
print("Ignore term", t)
continue
ptc = ftc / self._collection_length
# Fuses ptd for each object
ptd_fused = {}
for item in pr.keys():
doc_id = item
if doc_id in self.assoc_doc:
try:
ftd = self._elastic.term_freq(doc_id, term, self._field)
except: # the content of doc is empty
ftd = 0
doc_length = self._elastic.doc_length(doc_id, self._field)
ptd = ftd / doc_length
for object_id in self.assoc_doc[doc_id]:
if self._assoc_mode == FusionScorer.ASSOC_MODE_BINARY:
w_do = 1
elif self._assoc_mode == FusionScorer.ASSOC_MODE_UNIFORM:
w_do = 1 / len(self.assoc_obj[object_id])
else:
w_do = 0 # this should never happen
ptd_fused[object_id] = ptd_fused.get(object_id, 0) + ptd * w_do
# Adds pto to pqo
for object_id in self.assoc_obj.keys():
fptd = ptd_fused.get(object_id, 0)
pto = math.log((1 - self._lambda) * fptd + self._lambda * ptc) * ftq
pqo[object_id] = pqo.get(object_id, 0) + pto
return RetrievalResults(pqo)