Include inclusive too

Author: edvilme

Lib/statistics.py

@@ -1206,7 +1206,10 @@ def quantiles(data, *, n=4, method='exclusive'):
         result = []
         for i in range(1, n):
             j, delta = divmod(i * m, n)
-            interpolated = (data[j] * (n - delta) + data[j + 1] * delta) / n
+            if (data[j] == data[j + 1]) or not delta:
+                interpolated = data[j] / 1
+            else:
+                interpolated = (data[j] * (n - delta) + data[j + 1] * delta) / n
             result.append(interpolated)
         return result
 
@@ -1221,7 +1224,7 @@ def quantiles(data, *, n=4, method='exclusive'):
             # the interpolation formula which can be off by 1 ULP
             # due to floating-point rounding
             if (data[j - 1] == data[j]) or not delta:
-                interpolated = float(data[j - 1])
+                interpolated = data[j - 1] / 1
             else:
                 interpolated = (data[j - 1] * (n - delta) + data[j] * delta) / n
             result.append(interpolated)

Lib/test/test_statistics.py

@@ -2663,12 +2663,13 @@ def test_monotonic_with_duplicate_floats(self):
                   float.fromhex('0x1.fffffffffffffp+1023'),  # near max float
                   sys.float_info.min, # smallest normal
                   ):
-            for n in range(2, 20):
-                result = quantiles([x, x], n=n, method='exclusive')
-                self.assertEqual(result, sorted(result),
-                                 msg=f'x={x}, n={n}')
-                self.assertTrue(all(v == x for v in result),
-                                msg=f'x={x}, n={n}')
+            for method in ('exclusive', 'inclusive'):
+                for n in range(2, 20):
+                    result = quantiles([x, x], n=n, method=method)
+                    self.assertEqual(result, sorted(result),
+                                     msg=f'x={x}, n={n}, method={method!r}')
+                    self.assertTrue(all(v == x for v in result),
+                                    msg=f'x={x}, n={n}, method={method!r}')
 
     def test_equal_sized_groups(self):
         quantiles = statistics.quantiles