Merge pull request 'feat: Add a median function to the calculator' (#14) from typosaurus/13-add-a-median-function-to-the-calculator into main

Reviewed-on: #14

src/calculator.py

@@ -31,11 +31,15 @@ def average(values: list[int | float]) -> float:
     return sum(values) / len(values)
 
 
-def variance(values: Sequence[float]) -> float:
+def median(values: list[float]) -> float:
     if not values:
         raise ValueError
-    mean = sum(values) / len(values)
+    sorted_values = sorted(values)
-    return sum((x - mean) ** 2 for x in values) / len(values)
+    n = len(sorted_values)
+    mid = n // 2
+    if n % 2 == 1:
+        return sorted_values[mid]
+    return (sorted_values[mid - 1] + sorted_values[mid]) / 2.0
 
 
 def percentage(value: Union[int, float], total: Union[int, float]) -> float:
@@ -43,3 +47,10 @@ def percentage(value: Union[int, float], total: Union[int, float]) -> float:
         raise ValueError
     return (value / total) * 100
 
+
+def variance(values: Sequence[float]) -> float:
+    if not values:
+        raise ValueError
+    mean = sum(values) / len(values)
+    return sum((x - mean) ** 2 for x in values) / len(values)
+

src/typosaurus_sandbox/domain/calculator/__init__.py

@@ -1,7 +1,6 @@
 # retoor <retoor@molodetz.nl>
 
-from typosaurus_sandbox.domain.calculator.operations import add, average, clamp, clamp_to_byte, percentage, subtract, variance
+from typosaurus_sandbox.domain.calculator.operations import add, average, clamp, clamp_to_byte, median, percentage, subtract, variance
-
-__all__ = ["add", "average", "clamp", "clamp_to_byte", "percentage", "subtract", "variance"]
 
+__all__ = ["add", "average", "clamp", "clamp_to_byte", "median", "percentage", "subtract", "variance"]
 

src/typosaurus_sandbox/domain/calculator/operations.py

@@ -31,6 +31,17 @@ def average(values: list[int | float]) -> float:
     return sum(values) / len(values)
 
 
+def median(values: list[float]) -> float:
+    if not values:
+        raise ValueError
+    sorted_values = sorted(values)
+    n = len(sorted_values)
+    mid = n // 2
+    if n % 2 == 1:
+        return sorted_values[mid]
+    return (sorted_values[mid - 1] + sorted_values[mid]) / 2.0
+
+
 def variance(values: Sequence[float]) -> float:
     if not values:
         raise ValueError

tests/test_calculator.py

@@ -3,7 +3,7 @@
 import math
 import unittest
 
-from typosaurus_sandbox.domain.calculator import add, average, clamp, clamp_to_byte, subtract, variance
+from typosaurus_sandbox.domain.calculator import add, average, clamp, clamp_to_byte, median, subtract, variance
 
 
 class TestAddFunction(unittest.TestCase):
@@ -125,6 +125,32 @@ class TestClampFunction(unittest.TestCase):
         self.assertTrue(math.isnan(result))
 
 
+class TestMedianFunction(unittest.TestCase):
+
+    def test_odd_length_returns_middle_element(self) -> None:
+        self.assertEqual(median([1, 3, 5]), 3)
+
+    def test_even_length_returns_float_average_of_two_middle_values(self) -> None:
+        result = median([1, 2, 3, 4])
+        self.assertIsInstance(result, float)
+        self.assertEqual(result, 2.5)
+
+    def test_single_element_returns_that_element(self) -> None:
+        self.assertEqual(median([7]), 7)
+
+    def test_empty_list_raises_value_error(self) -> None:
+        with self.assertRaises(ValueError):
+            median([])
+
+    def test_unsorted_input_sorts_correctly(self) -> None:
+        self.assertEqual(median([3, 1, 2]), 2)
+
+    def test_unsorted_even_length_returns_float_average(self) -> None:
+        result = median([10, 30, 20, 40])
+        self.assertIsInstance(result, float)
+        self.assertEqual(result, 25.0)
+
+
 class TestVarianceFunction(unittest.TestCase):
 
     def test_empty_list_raises_value_error(self) -> None: