code sample for pandas-dev#42878

simonjayhawkins · Aug 4, 2021 · 59b75e6 · 59b75e6
1 parent 2555124
commit 59b75e6
Showing 1 changed file with 17 additions and 0 deletions.
diff --git a/bisect/42878.py b/bisect/42878.py
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+# BUG: [float32 precision] pandas float32 mean is inconsistent with numpy #42878
+
+import numpy as np
+
+import pandas as pd
+
+print(pd.__version__)
+
+a = pd.Series(np.random.normal(scale=0.1, size=(1_000_000,)).astype(np.float32)).pow(2)
+
+result = np.mean(a)
+print(result, type(result))
+
+expected = np.mean(a.values)
+assert isinstance(result, np.float32)
+assert isinstance(expected, np.float32)
+assert result == expected