ship with exact_match function already used ; don't call evaluate.load() on import (#2045)

lm_eval/api/metrics.py

 import logging
 import math
 import random
+import re
+import string
 from collections.abc import Iterable
 from typing import List
 
-import evaluate as hf_evaluate
 import numpy as np
 import sacrebleu
 import sklearn.metrics
@@ -166,7 +167,60 @@ def acc_mutual_info_fn(items):  # This is a passthrough function
     return items
 
 
-exact_match = hf_evaluate.load("exact_match")
+### the code used in the `exact_match_hf_evaluate` function is ported from
+### https://github.com/huggingface/evaluate/blob/main/metrics/exact_match/exact_match.py
+### which is under the apache license.
+
+# Copyright 2020 The HuggingFace Datasets Authors and the current dataset script contributor.
+
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+
+#     http://www.apache.org/licenses/LICENSE-2.0
+
+
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+def exact_match_hf_evaluate(
+    predictions,
+    references,
+    regexes_to_ignore=None,
+    ignore_case=False,
+    ignore_punctuation=False,
+    ignore_numbers=False,
+):
+    if regexes_to_ignore is not None:
+        for s in regexes_to_ignore:
+            predictions = np.array([re.sub(s, "", x) for x in predictions])
+            references = np.array([re.sub(s, "", x) for x in references])
+    else:
+        predictions = np.asarray(predictions)
+        references = np.asarray(references)
+
+    if ignore_case:
+        predictions = np.char.lower(predictions)
+        references = np.char.lower(references)
+
+    if ignore_punctuation:
+        repl_table = string.punctuation.maketrans("", "", string.punctuation)
+        predictions = np.char.translate(predictions, table=repl_table)
+        references = np.char.translate(references, table=repl_table)
+
+    if ignore_numbers:
+        repl_table = string.digits.maketrans("", "", string.digits)
+        predictions = np.char.translate(predictions, table=repl_table)
+        references = np.char.translate(references, table=repl_table)
+
+    score_list = predictions == references
+
+    return {"exact_match": np.mean(score_list)}
+
+
+###
 
 
 @register_metric(
@@ -176,7 +230,7 @@ exact_match = hf_evaluate.load("exact_match")
     aggregation="mean",
 )
 def exact_match_fn(**kwargs):
-    return exact_match.compute(**kwargs)
+    return exact_match_hf_evaluate(**kwargs)
 
 
 @register_metric(