File size: 783 Bytes
158b61b |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 |
#!/usr/bin/env python
from math import exp,log
class BleuScoreException(Exception):
pass
class BleuScorer:
def __init__(self):
"""References should be a list. If each element is a string, assume
they are filenames, if a list, assume tokenised strings"""
self.smooth = 1.0
self.order = 4
def score(self,scores):
if len(scores) != self.order*2+1:
raise BleuScoreException("Wrong number of scores. Expected %d, but found %d" %
(self.order*2+1, len(scores)))
logbleu = 0.0
for j in range(self.order):
logbleu += log(scores[2*j] + self.smooth) - log(scores[2*j+1] + self.smooth)
logbleu /= self.order
brevity = 1.0 - float(scores[-1]) / scores[1]
if brevity < 0:
logbleu += brevity
return exp(logbleu)
|