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xapianutils_bibrank_searcher.py
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xapianutils_bibrank_searcher.py
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# -*- coding: utf-8 -*-
##
## This file is part of Invenio.
## Copyright (C) 2011 CERN.
##
## Invenio is free software; you can redistribute it and/or
## modify it under the terms of the GNU General Public License as
## published by the Free Software Foundation; either version 2 of the
## License, or (at your option) any later version.
##
## Invenio is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
## General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Invenio; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
"""
Xapian utilities.
"""
from invenio.config import CFG_XAPIAN_ENABLED
from invenio.intbitset import intbitset
from invenio.xapianutils_config import INDEXES, XAPIAN_DIR
if CFG_XAPIAN_ENABLED:
import xapian
class MatchDecider(xapian.MatchDecider):
def __init__(self, ids):
xapian.MatchDecider.__init__(self)
self.ids = ids
def __call__(self, document):
return document.get_docid() in self.ids
DATABASES = dict()
def xapian_get_ranked_index(index, pattern, params, hitset, ranked_result_amount):
"""
Queries a Xapian index.
Returns: a list of ranked record ids [(recid, score), ...) contained in hitset
and an intbitset of record ids contained in hitset.
"""
result = []
matched_recs = intbitset()
database = DATABASES[index]
enquire = xapian.Enquire(database)
qp = xapian.QueryParser()
stemmer = xapian.Stem("english")
qp.set_stemmer(stemmer)
qp.set_database(database)
qp.set_stemming_strategy(xapian.QueryParser.STEM_SOME)
# Avoids phrase search to increase performance
if "avoid_phrase_search_threshold" in params and len(hitset) >= params["avoid_phrase_search_threshold"] and pattern.startswith('"'):
pattern = pattern[1:-1]
query_string = ' AND '.join(pattern.split(' '))
pattern = qp.parse_query(query_string)
else:
query_string = pattern
pattern = qp.parse_query(query_string, xapian.QueryParser.FLAG_PHRASE)
enquire.set_query(pattern)
matches = enquire.get_mset(0, ranked_result_amount, None, MatchDecider(hitset))
weight = params["weight"]
for match in matches:
recid = match.docid
if recid in hitset:
score = int(match.percent) * weight
result.append((recid, score))
matched_recs.add(recid)
return (result, matched_recs)
def xapian_init_databases():
"""
Initializes all database objects.
"""
for field in INDEXES:
database = xapian.Database(XAPIAN_DIR + "/" + field)
DATABASES[field] = database
def get_greatest_ranked_records(raw_reclist):
"""
Returns unique records having selecting the ones with the greatest records
in case of duplicates.
"""
unique_records = dict()
for (recid, score) in raw_reclist:
if not recid in unique_records:
unique_records[recid] = score
else:
current_score = unique_records[recid]
if score > current_score:
unique_records[recid] = score
result = []
for recid in unique_records.keys():
result.append((recid, unique_records[recid]))
return result
def word_similarity_xapian(pattern, hitset, params, verbose, field, ranked_result_amount):
"""
Ranking a records containing specified words and returns a sorted list.
input:
hitset - a list of hits for the query found by search_engine
verbose - verbose value
field - field to search (selected in GUI)
ranked_result_amount - amount of results to be ranked
output:
recset - a list of sorted records: [[23,34], [344,24], [1,01]]
prefix - what to show before the rank value
postfix - what to show after the rank value
voutput - contains extra information, content dependent on verbose value
"""
voutput = ""
search_units = []
if pattern:
xapian_init_databases()
pattern = " ".join(map(str, pattern))
from invenio.search_engine import create_basic_search_units
search_units = create_basic_search_units(None, pattern, field)
if verbose > 0:
voutput += "Hitset: %s<br/>" % hitset
voutput += "Pattern: %s<br/>" % pattern
voutput += "Search units: %s<br/>" % search_units
all_ranked_results = []
included_hits = intbitset()
excluded_hits = intbitset()
for (operator, pattern, field, unit_type) in search_units: #@UnusedVariable
# Field might not exist
if field not in params["fields"].keys():
field = params["default_field"]
if unit_type == "a":
# Eliminates leading and trailing %
if pattern[0] == "%":
pattern = pattern[1:-1]
pattern = "\"" + pattern + "\""
(ranked_result_part, matched_recs) = xapian_get_ranked_index(field, pattern, params["fields"][field], hitset, ranked_result_amount)
if verbose > 0:
voutput += "Index %s: %s<br/>" % (field, ranked_result_part)
voutput += "Index records %s: %s<br/>" % (field, matched_recs)
# Excludes - results
if operator == "-":
excluded_hits = excluded_hits.union(matched_recs)
# + and | are interpreted as OR
else:
included_hits = included_hits.union(matched_recs)
all_ranked_results.extend(ranked_result_part)
ranked_result = []
if hitset:
# Removes the excluded records
result_hits = included_hits.difference(excluded_hits)
# Avoids duplicate results and normalises scores
ranked_result = get_greatest_ranked_records(all_ranked_results)
ranked_result = get_normalized_ranking_scores(ranked_result)
# Considers not ranked records
not_ranked = hitset.difference(result_hits)
if not_ranked:
lrecIDs = list(not_ranked)
ranked_result = zip(lrecIDs, [0] * len(lrecIDs)) + ranked_result
if verbose > 0:
voutput += "All matched records: %s<br/>" % result_hits
voutput += "All ranked records: %s<br/>" % ranked_result
voutput += "All not ranked records: %s<br/>" % not_ranked
ranked_result.sort(lambda x, y: cmp(x[1], y[1]))
return (ranked_result, params["prefix"], params["postfix"], voutput)
return (ranked_result, "", "", voutput)
def get_normalized_ranking_scores(ranked_result):
max_score = 0
for res in ranked_result:
if res[1] > max_score:
max_score = res[1]
normalized_ranked_result = []
for res in ranked_result:
normalized_score = int(100.0 / max_score * res[1])
normalized_ranked_result.append((res[0], normalized_score))
return normalized_ranked_result

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