# This file is part of Lerot.
#
# Lerot is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Lerot 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with Lerot. If not, see <http://www.gnu.org/licenses/>.
import numpy as np
from .AbstractEval import AbstractEval
[docs]class DcgEval(AbstractEval):
"""Compute DCG (with gain = 2**rel-1 and log2 discount)."""
[docs] def get_dcg(self, ranked_labels, cutoff=-1):
"""
Get the dcg value of a list ranking.
Does not check if the numer for ranked labels is smaller than cutoff.
"""
if (cutoff == -1):
cutoff = len(ranked_labels)
rank = np.arange(cutoff)
return ((np.power(2, np.asarray(ranked_labels[:cutoff])) - 1) /
np.log2(2 + rank)).sum()
[docs] def evaluate_ranking(self, ranking, query, cutoff=-1):
"""
Compute DCG for the provided ranking. The ranking is expected
to contain document ids in rank order.
"""
if cutoff == -1 or cutoff > len(ranking):
cutoff = len(ranking)
# get labels for the sorted docids
sorted_labels = [0] * cutoff
for i in range(cutoff):
sorted_labels[i] = query.get_label(ranking[i])
return self.get_dcg(sorted_labels, cutoff)
[docs] def get_value(self, ranking, labels, orientations, cutoff=-1):
"""
Compute the value of the metric
- ranking contains the list of documents to evaluate
- labels are the relevance labels for all the documents, even those
that are not in the ranking; labels[doc.get_id()] is the relevance of
doc
- orientations contains orientation values for the verticals;
orientations[doc.get_type()] is the orientation value for the
doc (from 0 to 1).
"""
return self.get_dcg([labels[doc.get_id()] for doc in ranking], cutoff)