5.1 A function for the most common words

5.1 A function for the most common words

count gives the counts in no useful order. To find the most common words, tally must sort the counts, most common first, and keep the first few. A function, top, does it. It sorts by count, highest first, and then by the word, so that two words with the same count keep one order. Then it keeps the first n.

A patch to src/tally/__init__.py.

A test says what top must give. It gives top three words with their counts, and asks for the two most common.

A patch to tests/test_top.py.

In src/tally/__init__.py, top stands between count and main. It sorts with the key (-pair[1], pair[0]). The key is the count with a minus sign, so that the highest count comes first, and then the word. The new file tests/test_top.py has one test, test_most_common_first.

uv run python -m unittest discover -s tests -q

The four tests pass.

@@ -11,6 +11,11 @@ def count(text: str) -> dict[str, int]:
     return counts
 
 
+def top(counts: dict[str, int], n: int) -> list[tuple[str, int]]:
+    "The n most common words, most common first."
+    return sorted(counts.items(), key=lambda pair: (-pair[1], pair[0]))[:n]
+
+
 def main() -> None:
     text = open(sys.argv[1]).read() if len(sys.argv) > 1 else sys.stdin.read()
     for word, n in sorted(count(text).items()):

@@ -0,0 +1,8 @@
+import unittest
+
+from tally import top
+
+
+class Top(unittest.TestCase):
+    def test_most_common_first(self):
+        self.assertEqual(top({"a": 1, "b": 3, "c": 2}, 2), [("b", 3), ("c", 2)])