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-rwxr-xr-xper_sentence_bleu46
1 files changed, 18 insertions, 28 deletions
diff --git a/per_sentence_bleu b/per_sentence_bleu
index c7c0b0e..724b1e1 100755
--- a/per_sentence_bleu
+++ b/per_sentence_bleu
@@ -1,29 +1,21 @@
#!/usr/bin/env ruby
+require 'nlp_ruby'
require 'trollop'
-def ngrams_it(s, n, fix=false)
- a = s.strip.split
- a.each_with_index { |tok, i|
- tok.strip!
- 0.upto([n-1, a.size-i-1].min) { |m|
- yield a[i..i+m] if !(fix||(a[i..i+m].size>n))
- }
- }
-end
-
-def brevity_penalty hypothesis, reference
- a = hypothesis.split; b = reference.split
- return 1.0 if a.size>b.size
- return Math.exp(1.0 - ((b.size.to_f+1)/a.size));
+# reference-length hack as in (Nakov et al., 2012)
+def brevity_penalty hypothesis, reference, hack=0
+ a = tokenize hypothesis; b = tokenize reference
+ return 1.0 if a.size>=b.size
+ return Math.exp(1.0 - ((b.size.to_f+hack)/a.size));
end
-def per_sentence_bleu hypothesis, reference, n=4
+def per_sentence_bleu hypothesis, reference, n=4, hack=0
h_ng = {}; r_ng = {}
(1).upto(n) {|i| h_ng[i] = []; r_ng[i] = []}
- ngrams_it(hypothesis, n) {|i| h_ng[i.size] << i}
- ngrams_it(reference, n) {|i| r_ng[i.size] << i}
+ ngrams(hypothesis, n) {|i| h_ng[i.size] << i}
+ ngrams(reference, n) {|i| r_ng[i.size] << i}
m = [n, reference.split.size].min
weight = 1.0/m
add = 0.0
@@ -35,31 +27,29 @@ def per_sentence_bleu hypothesis, reference, n=4
add = 1.0 if i >= 2
sum += weight * Math.log((counts_clipped + add)/(counts_sum + add));
}
- return brevity_penalty(hypothesis, reference) * Math.exp(sum)
+ return brevity_penalty(hypothesis, reference, hack) * Math.exp(sum)
end
def main
- opts = Trollop::options do
+ cfg = Trollop::options do
opt :input, "input", :type => :string, :default => '-'
opt :references, "references", :type => :string, :required => true
+ opt :len_hack, "hack of Nakov et al", :type => :int, :default => 0
+ opt :n, "N", :default => 4
end
-
- refs = File.new(opts[:references], 'r').readlines.map{|i|i.strip}
+
+ refs = ReadFile.new(cfg[:references]).readlines_strip
i = -1
- if opts[:input] == '-'
- input = STDIN
- else
- input = File.new opts[:input], 'r'
- end
+ input = ReadFile.new cfg[:input]
while line = input.gets
i += 1
if line.strip == ''
puts 0.0
next
end
- puts per_sentence_bleu line.strip, refs[i]
+ puts per_sentence_bleu line.strip, refs[i], cfg[:n], cfg[:len_hack]
end
- input.close if opts[:input]!='-'
+ input.close
end