Add python3 examples for letor

code/python3/search_letor.py

@@ -0,0 +1,93 @@
+#!/usr/bin/env python
+#
+# Simple example script demonstrating how to re-rank using the trained model.
+#
+# Copyright (C) 2004,2005,2006,2007,2008,2009,2010,2015 Olly Betts
+# Copyright (C) 2011 Parth Gupta
+# Copyright (C) 2016 Ayush Tomar
+# Copyright (C) 2019 Vaibhav Kansagara
+#
+# This program 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.
+#
+# This program 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 this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
+# USA
+
+import sys
+import xapian
+import xapianletor
+
+# We require three command line arguments.
+if len(sys.argv) != 4:
+    print("Usage: %s DATABASE MSIZE QUERY" % sys.argv[0],
+          "NB: QUERY should be quoted to protect it from the shell.",
+          sep='\n', file=sys.stderr)
+    sys.exit(1)
+
+try:
+    db_path = sys.argv[1]
+    msize = sys.argv[2]
+    query_string = sys.argv[3]
+
+    db = xapian.Database(db_path)
+
+    parser = xapian.QueryParser()
+    parser.add_prefix("title", "S")
+    parser.add_prefix("subject", "S")
+    parser.set_database(db)
+    parser.set_default_op(xapian.Query.OP_OR)
+    parser.set_stemmer(xapian.Stem("en"))
+    parser.set_stemming_strategy(xapian.QueryParser.STEM_SOME)
+
+    query_no_prefix = parser.parse_query(query_string,
+                                         parser.FLAG_DEFAULT)
+    # query with title as default prefix
+    query_default_prefix = parser.parse_query(query_string,
+                                              parser.FLAG_DEFAULT,
+                                              "S")
+    # Combine queries
+    query = xapian.Query(xapian.Query.OP_OR, query_no_prefix, query_default_prefix)
+
+    enquire = xapian.Enquire(db)
+    enquire.set_query(query)
+
+    mset = enquire.get_mset(0, msize)
+
+    if mset.empty():
+        print("Empty MSet. No documents could be retrieved with the given Query.")
+        sys.exit(0)
+
+    print("Docids before re-ranking by LTR model:\n")
+    for m in mset:
+        print("%i: docid=%i [%s]" % (m.rank + 1, m.docid, m.document.get_data().decode('utf-8')))
+
+    # Initialise Ranker object with ListNETRanker instance, db path and query.
+    # See Ranker documentation for available Ranker subclass options.
+    ranker = xapianletor.ListNETRanker()
+    ranker.set_database_path(db_path)
+    ranker.set_query(query)
+
+    # Re-rank the existing mset using the letor model.
+    ranker.rank(mset)
+
+    print("Docids after re-ranking by LTR model:\n")
+
+    for m in mset:
+        print("%i: docid=%i [%s]" % (m.rank + 1, m.docid, m.document.get_data().decode('utf-8')))
+
+except xapian.QueryParserError as e:
+    print("Couldn't parse query: %s" % str(e), file=sys.stderr)
+    sys.exit(1)
+
+except Exception as e:
+    print("Exception: %s" % str(e), file=sys.stderr)
+    sys.exit(1)