Fix readability sentence boundary counting

assayer/scorer.py

@@ -1,9 +1,13 @@
 from __future__ import annotations
 
+import re
+
 from assayer.models import ModelResult
 
 _model = None
 
+_NON_BOUNDARY_ABBREVIATIONS = {"dr", "mr", "mrs", "ms", "prof", "sr", "jr", "st"}
+
 
 def _get_model():
     global _model
@@ -34,22 +38,57 @@ def compute_similarity(results: list[ModelResult]) -> dict[tuple[str, str], floa
     for i in range(len(valid)):
         for j in range(i + 1, len(valid)):
             score = float(np.dot(normalized[i], normalized[j]))
+            score = max(-1.0, min(1.0, score))
             similarity[(valid[i].model, valid[j].model)] = score
 
     return similarity
 
 
 def readability_stats(text: str) -> dict[str, float]:
-    sentences = [
-        s
-        for s in text.replace("!", ".").replace("?", ".").split(".")
-        if s.strip()
-    ]
     words = text.split()
     word_count = len(words)
-    sentence_count = len(sentences) or 1
+    sentence_count = _count_sentences(text)
     return {
         "word_count": float(word_count),
         "sentence_count": float(sentence_count),
         "avg_sentence_length": word_count / sentence_count,
     }
+
+
+def _count_sentences(text: str) -> int:
+    count = 0
+    start = 0
+
+    for match in re.finditer(r"[.!?]+", text):
+        punct_start, punct_end = match.span()
+        if punct_end < len(text) and not text[punct_end].isspace():
+            continue
+        if _is_non_boundary_period(text, punct_start, punct_end):
+            continue
+
+        if text[start:punct_end].strip():
+            count += 1
+        start = punct_end
+
+    if text[start:].strip():
+        count += 1
+
+    return count or 1
+
+
+def _is_non_boundary_period(text: str, punct_start: int, punct_end: int) -> bool:
+    if text[punct_start] != ".":
+        return False
+    if (
+        punct_start > 0
+        and punct_start + 1 < len(text)
+        and text[punct_start - 1].isdigit()
+        and text[punct_start + 1].isdigit()
+    ):
+        return True
+
+    token_match = re.search(r"([A-Za-z]+)\.$", text[:punct_end])
+    if not token_match:
+        return False
+
+    return token_match.group(1).lower() in _NON_BOUNDARY_ABBREVIATIONS

tests/test_scorer.py

@@ -73,6 +73,20 @@ def test_readability_stats_basic():
     assert stats["avg_sentence_length"] == pytest.approx(8 / 3)
 
 
+@pytest.mark.parametrize(
+    ("text", "sentence_count"),
+    [
+        ("Dr. Smith scored 3.5. Well done.", 2),
+        ("Visit example.com for details.", 1),
+        ("The price is $3.99. Cheap!", 2),
+        ("Mr. Jones paid at 4.30 p.m. Done?", 2),
+    ],
+)
+def test_readability_stats_ignores_non_boundary_periods(text, sentence_count):
+    stats = readability_stats(text)
+    assert stats["sentence_count"] == sentence_count
+
+
 def test_readability_stats_empty():
     stats = readability_stats("")
     assert stats["word_count"] == 0