File size: 6,110 Bytes
650c5f6
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
#!/usr/bin/env python3
# Copyright (c) Facebook, Inc. and its affiliates.
#
# This source code is licensed under the MIT license found in the
# LICENSE file in the root directory of this source tree.
"""
Scoring script for computing pairwise BLEU and multi-ref BLEU over a set of
candidate hypotheses.

See `"Mixture Models for Diverse Machine Translation: Tricks of the Trade"
(Shen et al., 2019) <https://arxiv.org/abs/1902.07816>`_.
"""

import argparse
import random
import sys
from itertools import chain

import numpy as np
from sacrebleu import compute_bleu, corpus_bleu as _corpus_bleu


def main():
    parser = argparse.ArgumentParser(sys.argv[0])
    parser.add_argument(
        "--sys", nargs="*", default="", metavar="FILE", help="path to system output"
    )
    parser.add_argument("--ref", default="", metavar="FILE", help="path to references")
    parser.add_argument(
        "--output",
        default="",
        metavar="FILE",
        help="print outputs into a pretty format",
    )
    args = parser.parse_args()

    if args.sys:
        src, tgt, hypos, log_probs = load_sys(args.sys)
        print("pairwise BLEU: %.2f" % pairwise(hypos))
        if args.output:
            merge(src, tgt, hypos, log_probs, args.output)

    if args.ref:
        _, _, refs = load_ref(args.ref)
        if args.sys:
            multi_ref(refs, hypos)
        else:
            intra_ref(refs)


def dictolist(d):
    a = sorted(d.items(), key=lambda i: i[0])
    return [i[1] for i in a]


def load_sys(paths):
    src, tgt, hypos, log_probs = {}, {}, {}, {}
    for path in paths:
        with open(path) as f:
            for line in f:
                line = line.rstrip()
                # S: source
                # T: target
                # D: detokenized system output
                if line.startswith(("S-", "T-", "D-")):
                    i = int(line[line.find("-") + 1 : line.find("\t")])
                    if line.startswith("S-"):
                        src[i] = line.split("\t")[1]
                    if line.startswith("T-"):
                        tgt[i] = line.split("\t")[1]
                    if line.startswith("D-"):
                        if i not in hypos:
                            hypos[i] = []
                            log_probs[i] = []
                        hypos[i].append(line.split("\t")[2])
                        log_probs[i].append(float(line.split("\t")[1]))
    return dictolist(src), dictolist(tgt), dictolist(hypos), dictolist(log_probs)


def load_ref(path):
    with open(path) as f:
        lines = f.readlines()
    src, tgt, refs = [], [], []
    i = 0
    while i < len(lines):
        if lines[i].startswith("S-"):
            src.append(lines[i].split("\t")[1].rstrip())
            i += 1
        elif lines[i].startswith("T-"):
            tgt.append(lines[i].split("\t")[1].rstrip())
            i += 1
        else:
            a = []
            while i < len(lines) and lines[i].startswith("R"):
                a.append(lines[i].split("\t")[1].rstrip())
                i += 1
            refs.append(a)
    return src, tgt, refs


def merge(src, tgt, hypos, log_probs, path):
    with open(path, "w") as f:
        for s, t, hs, lps in zip(src, tgt, hypos, log_probs):
            f.write(s + "\n")
            f.write(t + "\n")
            f.write("\n")
            for h, lp in zip(hs, lps):
                f.write("\t%f\t%s\n" % (lp, h.strip()))
            f.write("------------------------------------------------------\n")


def corpus_bleu(sys_stream, ref_streams):
    bleu = _corpus_bleu(sys_stream, ref_streams, tokenize="none")
    return bleu.score


def sentence_bleu(hypothesis, reference):
    bleu = _corpus_bleu(hypothesis, reference)
    for i in range(1, 4):
        bleu.counts[i] += 1
        bleu.totals[i] += 1
    bleu = compute_bleu(
        bleu.counts,
        bleu.totals,
        bleu.sys_len,
        bleu.ref_len,
        smooth_method="exp",
    )
    return bleu.score


def pairwise(sents):
    _ref, _hypo = [], []
    for s in sents:
        for i in range(len(s)):
            for j in range(len(s)):
                if i != j:
                    _ref.append(s[i])
                    _hypo.append(s[j])
    return corpus_bleu(_hypo, [_ref])


def multi_ref(refs, hypos):
    _ref, _hypo = [], []
    ref_cnt = 0
    assert len(refs) == len(hypos)

    # count number of refs covered
    for rs, hs in zip(refs, hypos):
        a = set()
        for h in hs:
            s = [sentence_bleu(h, r) for r in rs]
            j = np.argmax(s)
            _ref.append(rs[j])
            _hypo.append(h)
            best = [k for k in range(len(rs)) if s[k] == s[j]]
            a.add(random.choice(best))
        ref_cnt += len(a)
    print("#refs covered: %.2f" % (ref_cnt / len(refs)))

    # transpose refs and hypos
    refs = list(zip(*refs))
    hypos = list(zip(*hypos))

    # compute multi-ref corpus BLEU (leave-one-out to be comparable to intra_ref)
    k = len(hypos)
    m = len(refs)
    flat_hypos = [hypos[j][i] for i in range(len(hypos[0])) for j in range(k)]
    duplicated_refs = [[ref for ref in refs_i for _ in range(k)] for refs_i in refs]
    loo_bleus = []
    for held_out_ref in range(m):
        remaining_refs = (
            duplicated_refs[:held_out_ref] + duplicated_refs[held_out_ref + 1 :]
        )
        assert len(remaining_refs) == m - 1
        loo_bleus.append(corpus_bleu(flat_hypos, remaining_refs))
    print("average multi-reference BLEU (leave-one-out): %.2f" % np.mean(loo_bleus))


def intra_ref(refs):
    print("ref pairwise BLEU: %.2f" % pairwise(refs))
    refs = list(zip(*refs))
    m = len(refs)
    concat_h = []
    concat_rest = [[] for j in range(m - 1)]
    for i, h in enumerate(refs):
        rest = refs[:i] + refs[i + 1 :]
        concat_h.append(h)
        for j in range(m - 1):
            concat_rest[j].extend(rest[j])
    concat_h = list(chain.from_iterable(concat_h))
    bleu = corpus_bleu(concat_h, concat_rest)
    print("multi-reference BLEU (leave-one-out): %.2f" % bleu)


if __name__ == "__main__":
    main()