updates

Backend/venv/lib/python3.12/site-packages/nltk/translate/metrics.py

@@ -0,0 +1,41 @@
+# Natural Language Toolkit: Translation metrics
+#
+# Copyright (C) 2001-2025 NLTK Project
+# Author: Will Zhang <wilzzha@gmail.com>
+#         Guan Gui <ggui@student.unimelb.edu.au>
+#         Steven Bird <stevenbird1@gmail.com>
+# URL: <https://www.nltk.org/>
+# For license information, see LICENSE.TXT
+
+
+def alignment_error_rate(reference, hypothesis, possible=None):
+    """
+    Return the Alignment Error Rate (AER) of an alignment
+    with respect to a "gold standard" reference alignment.
+    Return an error rate between 0.0 (perfect alignment) and 1.0 (no
+    alignment).
+
+        >>> from nltk.translate import Alignment
+        >>> ref = Alignment([(0, 0), (1, 1), (2, 2)])
+        >>> test = Alignment([(0, 0), (1, 2), (2, 1)])
+        >>> alignment_error_rate(ref, test) # doctest: +ELLIPSIS
+        0.6666666666666667
+
+    :type reference: Alignment
+    :param reference: A gold standard alignment (sure alignments)
+    :type hypothesis: Alignment
+    :param hypothesis: A hypothesis alignment (aka. candidate alignments)
+    :type possible: Alignment or None
+    :param possible: A gold standard reference of possible alignments
+        (defaults to *reference* if None)
+    :rtype: float or None
+    """
+
+    if possible is None:
+        possible = reference
+    else:
+        assert reference.issubset(possible)  # sanity check
+
+    return 1.0 - (len(hypothesis & reference) + len(hypothesis & possible)) / float(
+        len(hypothesis) + len(reference)
+    )