Fix bug in meteor (nltk#2619)

* passing preprocess arg to single_meteor_score function call

* adding test case

* updating authors

AUTHORS.md

@@ -270,6 +270,7 @@
 - Jacob Moorman <https://github.com/jdmoorman>
 - Cory Nezin <https://github.com/corynezin>
 - Matt Chaput
+- Akshita Bhagia <https://github.com/AkshitaB>
 
 ## Others whose work we've taken and included in NLTK, but who didn't directly contribute it:
 ### Contributors to the Porter Stemmer

nltk/test/unit/translate/test_meteor.py

@@ -0,0 +1,16 @@
+import unittest
+
+from nltk.translate.meteor_score import meteor_score
+
+class TestMETEOR(unittest.TestCase):
+    def test_preprocess(self):
+        # Using lists instead of strings specifically to demonstrate use of `preprocess`.
+        reference = [['this', 'is', 'a', 'test'], ['this', 'is' 'test']]
+        candidate = ['this', 'is', 'a', 'test']
+
+        # no `preprocess` argument
+        self.assertRaises(TypeError, meteor_score, reference, candidate)
+
+        # with `preprocess` argument
+        score = meteor_score(reference, candidate, preprocess=lambda x: ' '.join(x))
+        assert score == 0.9921875

nltk/translate/meteor_score.py

@@ -421,6 +421,7 @@ def meteor_score(
             single_meteor_score(
                 reference,
                 hypothesis,
+                preprocess=preprocess,
                 stemmer=stemmer,
                 wordnet=wordnet,
                 alpha=alpha,