TheAlgorithms · hunter-bradley-akash-code · Aug 11, 2026 · Aug 11, 2026 · Aug 11, 2026
diff --git a/maths/harmonic_mean.py b/maths/harmonic_mean.py
@@ -0,0 +1,35 @@
+from __future__ import annotations
+
+
+def harmonic_mean(numbers: list[int | float]) -> float:
+    """
+    Return the harmonic mean of a sequence of numbers.
+
+    Reference: https://en.wikipedia.org/wiki/Harmonic_mean
+
+    >>> harmonic_mean([1, 2, 4])
+    1.7142857142857142
+    >>> harmonic_mean([2, 2, 2])
+    2.0
+    >>> harmonic_mean([])
+    Traceback (most recent call last):
+    ...
+    ValueError: harmonic_mean() arg is an empty sequence
+    >>> harmonic_mean([1, 0, 2])
+    Traceback (most recent call last):
+    ...
+    ValueError: harmonic mean is undefined for zero values
+    """
+    if not numbers:
+        raise ValueError("harmonic_mean() arg is an empty sequence")
+
+    if any(number == 0 for number in numbers):
+        raise ValueError("harmonic mean is undefined for zero values")
+
+    return len(numbers) / sum(1 / number for number in numbers)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod(verbose=True)