def get_terms(request):
"""Given an ajax request, return, in a json, the index terms"""
context = request.REQUEST.get('context')
lang = request.REQUEST.get('lang', 'en')
service = request.REQUEST.get('service')
service = service if service in WEB_SERVICES.keys() or not service else 'yahoo'
use_service = bool(service)
if context:
terms = build_query(context, language=lang, use_web_service=use_service, web_service=service)
else:
terms = ""
if request.is_ajax():
return HttpResponse(json.dumps({'terms': terms}, ensure_ascii=False), mimetype="application/json")
else:
return HttpResponse(terms, mimetype="text/plain")
def get_recommendations(request):
#get the terms
context = request.REQUEST['context']
lang = request.REQUEST.get('lang', 'en')
#default to a supported language:
lang = lang if lang in [e[0] for e in settings.LANGUAGES] else 'en'
service = request.REQUEST.get('service', '')
service = service if service in WEB_SERVICES.keys() or (not service and lang == 'en') else "yahoo"#'tagthe'
use_service = bool(service)
try:
terms = build_query(context, language=lang, use_web_service=use_service, web_service=service, fail_silently=False)
except:
return HttpResponseServerError("Error extracting terms")
#do the search
results = do_search(terms, lang=lang)
#re-rank
if hasattr(request, 'profile'):
results=re_rank(request.profile, results)
else:
return HttpResponseBadRequest("No profile found")
#return
return {'results': results, 'terms': unicode(terms)}
def update_profile(profile, context, docs, lang='en', terms=True, **kwargs):
"""Update a profile with a spreading activation algorithm: determine the concepts in which the user might be interested,
save the session and update the activation values, proceeding then to update the profile itself
Args:
profile: the client user
context: the last context terms or text
docs: the ids of the documents of our database the user found interesting
lang: the language of the user
terms: whether the context is already a string of index terms or a full text
"""
#build the context list:
#context = context + list(DocumentSurrogate.)
lang = lang if lang in [e[0] for e in settings.LANGUAGES] else 'en'
#STEP 0: build the concepts set and set their activation values:
CON = {}
if not terms and context:
context = build_query(context, language=lang)
if not hasattr(context, '__iter__'):
context = [context,]
#Populate the concepts list with a dictionary of the form {concept: similarity}
for d in context:
CON.update(DmozCategory.get_for_query(d, lang, as_dict=True))
for d in DocumentSurrogate.objects.filter(pk__in=docs).values_list('category', flat=True).iterator():
#TODO: should I compute the document's summary similarity to its alleged category?
CON.update({d:1.0})
#logging.debug("Concepts gathered %s" % CON)
#Spreading: add to the interest list the attenuated weight of it's ancestors:
for c in CON.keys():
curr_concept = c
parent = DmozCategory.objects.filter(pk=curr_concept).values_list('parent', flat=True)[0]
while parent:
#multiple children of a parent might be in CON, ensure that the maximum score is the one that survives
#by selecting the maximum each time
ch_weight= DmozCategory.objects.filter(pk=curr_concept).values_list('weight', flat=True)[0]
CON.update({parent: max(CON.get(parent, 0.0), CON[curr_concept] * ch_weight)})
curr_concept = parent
parent = DmozCategory.objects.filter(pk=curr_concept).values_list('parent', flat=True)[0]
#logging.debug("After propagation: %s" % CON)
#STEP 2: Evolve the profile
#Use linear combination to update
existing_preferences = []
#logging.debug("Profile before update: %s" % profile.preferences.all())
for preference in profile.preferences.iterator():
#if the preference is not in this session, decay
ctg = preference.category.pk
if not ctg in CON:
preference.score = DECAY*preference.score
else: #it is, augment:
preference.score = DECAY*preference.score + (1-DECAY)*CON[ctg]
preference.save()
#add the preference to the set of existing ones:
existing_preferences += [ctg,]
#determine which preferences to add to the profile:
to_add = set(CON.keys()) - set(existing_preferences)
for newcat in to_add:
#pref = ClientPreference(category=DmozCategory.objects.get(pk=c), score=CON[newcat], user=profile)
#DO NOT store zero weighted preferences:
if CON[newcat]:
new_pref = ClientPreference(category_id=newcat, score=CON[newcat], user=profile)
new_pref.save()
#logging.debug("Profile after update: %s" %profile.preferences.all())
return True
