#!/usr/bin/env python
"""
@package eWRT.ws.stat.eval.metrics
Standard IR evaluation metrics such as
* precision
* recall
* F1 measure
"""
# (C)opyrights 2010 by Albert Weichselbraun <albert@weichselbraun.net>
# and others (as outlined in the functions.
#
# The code published in this module is either under the GNU General
# Public License (see below) or under the license specified in the
# function.
#
# 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 3 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, see <http://www.gnu.org/licenses/>.
#
[docs]def precision(relevant, retrieved):
""" returns the precision of the given sets
@param[in] relevant set of relevant terms
@param[in] retrieved set of retrieved terms
@returns the precision
"""
assert isinstance(relevant, set)
assert isinstance(retrieved, set)
return float( len(relevant.intersection(retrieved)) ) / len(retrieved)
[docs]def recall(relevant, retrieved):
""" returns the recall of the given sets
@param[in] relevant set of relevant terms
@param[in] retrieved set of retrieved terms
@returns the recall
"""
assert isinstance(relevant, set)
assert isinstance(retrieved, set)
return float( len(relevant.intersection(retrieved)) ) / len(relevant)
[docs]def fMeasure(p, r, beta=1.):
""" returns the F-measure for the given precision and recall
@param[in] p precision
@param[in] r recall
@param[in] beta weight used to compute the f mesure
@returns the F-Measure
"""
return (1+beta*beta) * (p*r)/(beta*beta*p+r)
[docs]class TestEvaluationMetrics(object):
""" tests the evaluation metrics """
a = set( (1,3,8,9) )
b = set( (1,3,10,12) )
c = set( (1,3) )
d = set( (10, 11) )
[docs] def testPrecision(self):
assert precision(self.a, self.b) == 0.5
assert precision(self.a, self.a) == 1.0
assert precision(self.a, self.c) == 1.0
assert precision(self.a, self.d) == 0.0
[docs] def testRecall(self):
assert recall(self.a, self.a) == 1.0
assert recall(self.a, self.b) == 0.5
assert recall(self.a, self.c) == 0.5
assert recall(self.a, self.d) == 0.0
[docs] def testFMeasure(self):
assert fMeasure(1.,1.,1.) == 1
assert fMeasure(1.,0.,1.) == 0.0
assert fMeasure(1.,0.5,1.) == 1/1.5