"""Official evaluation script for SQuAD version 2.0.
In addition to basic functionality, we also compute additional statistics and
plot precision-recall curves if an additional na_prob.json file is provided.
This file is expected to map question ID's to the model's predicted probability
that a question is unanswerable.
"""
import argparse
import collections
import json
import numpy as np
import os
import re
import string
import sys
OPTS = None
[docs]def parse_args(): # pragma: no cover
parser = argparse.ArgumentParser("Official evaluation script for SQuAD version 2.0.")
parser.add_argument("data_file", metavar="data.json", help="Input data JSON file.")
parser.add_argument("pred_file", metavar="pred.json", help="Model predictions.")
parser.add_argument(
"--out-file",
"-o",
metavar="eval.json",
help="Write accuracy metrics to file (default is stdout).",
)
parser.add_argument(
"--na-prob-file",
"-n",
metavar="na_prob.json",
help="Model estimates of probability of no answer.",
)
parser.add_argument(
"--na-prob-thresh",
"-t",
type=float,
default=1.0,
help='Predict "" if no-answer probability exceeds this (default = 1.0).',
)
parser.add_argument(
"--out-image-dir",
"-p",
metavar="out_images",
default=None,
help="Save precision-recall curves to directory.",
)
parser.add_argument("--verbose", "-v", action="store_true")
if len(sys.argv) == 1:
parser.print_help()
sys.exit(1)
return parser.parse_args()
[docs]def make_qid_to_has_ans(dataset): # pragma: no cover
qid_to_has_ans = {}
for article in dataset:
for p in article["paragraphs"]:
for qa in p["qas"]:
qid_to_has_ans[qa["id"]] = bool(qa["answers"])
return qid_to_has_ans
[docs]def normalize_answer(s): # pragma: no cover
"""Lower text and remove punctuation, articles and extra whitespace."""
def remove_articles(text):
regex = re.compile(r"\b(a|an|the)\b", re.UNICODE)
return re.sub(regex, " ", text)
def white_space_fix(text):
return " ".join(text.split())
def remove_punc(text):
exclude = set(string.punctuation)
return "".join(ch for ch in text if ch not in exclude)
def lower(text):
return text.lower()
return white_space_fix(remove_articles(remove_punc(lower(s))))
[docs]def get_tokens(s): # pragma: no cover
if not s:
return []
return normalize_answer(s).split()
[docs]def compute_exact(a_gold, a_pred): # pragma: no cover
return int(normalize_answer(a_gold) == normalize_answer(a_pred))
[docs]def compute_f1(a_gold, a_pred): # pragma: no cover
gold_toks = get_tokens(a_gold)
pred_toks = get_tokens(a_pred)
common = collections.Counter(gold_toks) & collections.Counter(pred_toks)
num_same = sum(common.values())
if len(gold_toks) == 0 or len(pred_toks) == 0:
# If either is no-answer, then F1 is 1 if they agree, 0 otherwise
return int(gold_toks == pred_toks)
if num_same == 0:
return 0
precision = 1.0 * num_same / len(pred_toks)
recall = 1.0 * num_same / len(gold_toks)
f1 = (2 * precision * recall) / (precision + recall)
return f1
[docs]def get_raw_scores(dataset, preds): # pragma: no cover
exact_scores = {}
f1_scores = {}
for article in dataset:
for p in article["paragraphs"]:
for qa in p["qas"]:
qid = qa["id"]
gold_answers = [a["text"] for a in qa["answers"] if normalize_answer(a["text"])]
if not gold_answers:
# For unanswerable questions, only correct answer is empty
# string
gold_answers = [""]
if qid not in preds:
# print('Missing prediction for %s' % qid)
continue
a_pred = preds[qid]
# Take max over all gold answers
exact_scores[qid] = max(compute_exact(a, a_pred) for a in gold_answers)
f1_scores[qid] = max(compute_f1(a, a_pred) for a in gold_answers)
return exact_scores, f1_scores
[docs]def apply_no_ans_threshold(scores, na_probs, qid_to_has_ans, na_prob_thresh): # pragma: no cover
new_scores = {}
for qid, s in scores.items():
pred_na = na_probs[qid] > na_prob_thresh
if pred_na:
new_scores[qid] = float(not qid_to_has_ans[qid])
else:
new_scores[qid] = s
return new_scores
[docs]def make_eval_dict(exact_scores, f1_scores, qid_list=None): # pragma: no cover
if not qid_list:
total = len(exact_scores)
return collections.OrderedDict(
[
("exact", 100.0 * sum(exact_scores.values()) / total),
("f1", 100.0 * sum(f1_scores.values()) / total),
("total", total),
]
)
else:
total = len(qid_list)
return collections.OrderedDict(
[
("exact", 100.0 * sum(exact_scores[k] for k in qid_list) / total),
("f1", 100.0 * sum(f1_scores[k] for k in qid_list) / total),
("total", total),
]
)
[docs]def merge_eval(main_eval, new_eval, prefix): # pragma: no cover
for k in new_eval:
main_eval["%s_%s" % (prefix, k)] = new_eval[k]
[docs]def plot_pr_curve(precisions, recalls, out_image, title): # pragma: no cover
plt.step(recalls, precisions, color="b", alpha=0.2, where="post")
plt.fill_between(recalls, precisions, step="post", alpha=0.2, color="b")
plt.xlabel("Recall")
plt.ylabel("Precision")
plt.xlim([0.0, 1.05])
plt.ylim([0.0, 1.05])
plt.title(title)
plt.savefig(out_image)
plt.clf()
[docs]def make_precision_recall_eval(
scores, na_probs, num_true_pos, qid_to_has_ans, out_image=None, title=None
): # pragma: no cover
qid_list = sorted(na_probs, key=lambda k: na_probs[k])
true_pos = 0.0
cur_p = 1.0
cur_r = 0.0
precisions = [1.0]
recalls = [0.0]
avg_prec = 0.0
for i, qid in enumerate(qid_list):
if qid_to_has_ans[qid]:
true_pos += scores[qid]
cur_p = true_pos / float(i + 1)
cur_r = true_pos / float(num_true_pos)
if i == len(qid_list) - 1 or na_probs[qid] != na_probs[qid_list[i + 1]]:
# i.e., if we can put a threshold after this point
avg_prec += cur_p * (cur_r - recalls[-1])
precisions.append(cur_p)
recalls.append(cur_r)
if out_image:
plot_pr_curve(precisions, recalls, out_image, title)
return {"ap": 100.0 * avg_prec}
[docs]def run_precision_recall_analysis(
main_eval, exact_raw, f1_raw, na_probs, qid_to_has_ans, out_image_dir
): # pragma: no cover
if out_image_dir and not os.path.exists(out_image_dir):
os.makedirs(out_image_dir)
num_true_pos = sum(1 for v in qid_to_has_ans.values() if v)
if num_true_pos == 0:
return
pr_exact = make_precision_recall_eval(
exact_raw,
na_probs,
num_true_pos,
qid_to_has_ans,
out_image=os.path.join(out_image_dir, "pr_exact.png"),
title="Precision-Recall curve for Exact Match score",
)
pr_f1 = make_precision_recall_eval(
f1_raw,
na_probs,
num_true_pos,
qid_to_has_ans,
out_image=os.path.join(out_image_dir, "pr_f1.png"),
title="Precision-Recall curve for F1 score",
)
oracle_scores = {k: float(v) for k, v in qid_to_has_ans.items()}
pr_oracle = make_precision_recall_eval(
oracle_scores,
na_probs,
num_true_pos,
qid_to_has_ans,
out_image=os.path.join(out_image_dir, "pr_oracle.png"),
title="Oracle Precision-Recall curve (binary task of HasAns vs. NoAns)",
)
merge_eval(main_eval, pr_exact, "pr_exact")
merge_eval(main_eval, pr_f1, "pr_f1")
merge_eval(main_eval, pr_oracle, "pr_oracle")
[docs]def histogram_na_prob(na_probs, qid_list, image_dir, name): # pragma: no cover
if not qid_list:
return
x = [na_probs[k] for k in qid_list]
weights = np.ones_like(x) / float(len(x))
plt.hist(x, weights=weights, bins=20, range=(0.0, 1.0))
plt.xlabel("Model probability of no-answer")
plt.ylabel("Proportion of dataset")
plt.title("Histogram of no-answer probability: %s" % name)
plt.savefig(os.path.join(image_dir, "na_prob_hist_%s.png" % name))
plt.clf()
[docs]def find_best_thresh(preds, scores, na_probs, qid_to_has_ans): # pragma: no cover
num_no_ans = sum(1 for k in qid_to_has_ans if not qid_to_has_ans[k])
cur_score = num_no_ans
best_score = cur_score
best_thresh = 0.0
qid_list = sorted(na_probs, key=lambda k: na_probs[k])
for i, qid in enumerate(qid_list):
if qid not in scores:
continue
if qid_to_has_ans[qid]:
diff = scores[qid]
else:
if preds[qid]:
diff = -1
else:
diff = 0
cur_score += diff
if cur_score > best_score:
best_score = cur_score
best_thresh = na_probs[qid]
return 100.0 * best_score / len(scores), best_thresh
[docs]def find_all_best_thresh(
main_eval, preds, exact_raw, f1_raw, na_probs, qid_to_has_ans
): # pragma: no cover
best_exact, exact_thresh = find_best_thresh(preds, exact_raw, na_probs, qid_to_has_ans)
best_f1, f1_thresh = find_best_thresh(preds, f1_raw, na_probs, qid_to_has_ans)
main_eval["best_exact"] = best_exact
main_eval["best_exact_thresh"] = exact_thresh
main_eval["best_f1"] = best_f1
main_eval["best_f1_thresh"] = f1_thresh
[docs]def evaluate(dataset, na_probs, preds, na_prob_thresh=1.0):
qid_to_has_ans = make_qid_to_has_ans(dataset) # maps qid to True/False
has_ans_qids = [k for k, v in qid_to_has_ans.items() if v]
no_ans_qids = [k for k, v in qid_to_has_ans.items() if not v]
exact_raw, f1_raw = get_raw_scores(dataset, preds)
exact_thresh = apply_no_ans_threshold(exact_raw, na_probs, qid_to_has_ans, na_prob_thresh)
f1_thresh = apply_no_ans_threshold(f1_raw, na_probs, qid_to_has_ans, na_prob_thresh)
out_eval = make_eval_dict(exact_thresh, f1_thresh)
if has_ans_qids:
has_ans_eval = make_eval_dict(exact_thresh, f1_thresh, qid_list=has_ans_qids)
merge_eval(out_eval, has_ans_eval, "HasAns")
if no_ans_qids:
no_ans_eval = make_eval_dict(exact_thresh, f1_thresh, qid_list=no_ans_qids)
merge_eval(out_eval, no_ans_eval, "NoAns")
find_all_best_thresh(out_eval, preds, exact_raw, f1_raw, na_probs, qid_to_has_ans)
return out_eval
[docs]def main(): # pragma: no cover
with open(OPTS.data_file) as f:
dataset_json = json.load(f)
dataset = dataset_json["data"]
with open(OPTS.pred_file) as f:
preds = json.load(f)
if OPTS.na_prob_file:
with open(OPTS.na_prob_file) as f:
na_probs = json.load(f)
else:
na_probs = {k: 0.0 for k in preds}
qid_to_has_ans = make_qid_to_has_ans(dataset) # maps qid to True/False
has_ans_qids = [k for k, v in qid_to_has_ans.items() if v]
no_ans_qids = [k for k, v in qid_to_has_ans.items() if not v]
exact_raw, f1_raw = get_raw_scores(dataset, preds)
exact_thresh = apply_no_ans_threshold(exact_raw, na_probs, qid_to_has_ans, OPTS.na_prob_thresh)
f1_thresh = apply_no_ans_threshold(f1_raw, na_probs, qid_to_has_ans, OPTS.na_prob_thresh)
out_eval = make_eval_dict(exact_thresh, f1_thresh)
if has_ans_qids:
has_ans_eval = make_eval_dict(exact_thresh, f1_thresh, qid_list=has_ans_qids)
merge_eval(out_eval, has_ans_eval, "HasAns")
if no_ans_qids:
no_ans_eval = make_eval_dict(exact_thresh, f1_thresh, qid_list=no_ans_qids)
merge_eval(out_eval, no_ans_eval, "NoAns")
if OPTS.na_prob_file:
find_all_best_thresh(out_eval, preds, exact_raw, f1_raw, na_probs, qid_to_has_ans)
if OPTS.na_prob_file and OPTS.out_image_dir:
run_precision_recall_analysis(
out_eval, exact_raw, f1_raw, na_probs, qid_to_has_ans, OPTS.out_image_dir
)
histogram_na_prob(na_probs, has_ans_qids, OPTS.out_image_dir, "hasAns")
histogram_na_prob(na_probs, no_ans_qids, OPTS.out_image_dir, "noAns")
if OPTS.out_file:
with open(OPTS.out_file, "w") as f:
json.dump(out_eval, f)
else:
print(json.dumps(out_eval, indent=2))
if __name__ == "__main__": # pragma: no cover
OPTS = parse_args()
if OPTS.out_image_dir:
import matplotlib
matplotlib.use("Agg")
import matplotlib.pyplot as plt
main()