code sample for pandas-dev#42452

Author: simonjayhawkins

bisect/42452.py

@@ -0,0 +1,18 @@
+# BUG: pandas EWM fails silently if data types are float32 instead of float64 #42452
+
+import numpy as np
+
+import pandas as pd
+from pandas import DataFrame
+import pandas._testing as tm
+
+print(pd.__version__)
+
+float_dtype = np.float32
+df = DataFrame({"A": range(5), "B": range(10, 15)}, dtype=float_dtype)
+
+result = df.rolling(2, axis=1).sum()
+print(result)
+
+expected = DataFrame({"A": [np.nan] * 5, "B": range(10, 20, 2)}, dtype=float_dtype)
+tm.assert_frame_equal(result, expected, check_dtype=False)