code sample for pandas-dev#46634

Author: simonjayhawkins

bisect/46634.py

@@ -0,0 +1,27 @@
+# BUG: Replace changes the dtype of other columns #46634
+
+import pandas as pd
+
+print(pd.__version__)
+
+cat_series = pd.Series(["b", "b", "b", "d"], dtype="category")
+df = pd.DataFrame(
+    {
+        "id": pd.Series([5, 4, 3, 2], dtype="float64"),
+        "col": cat_series,
+    }
+)
+result = df.replace({3: None})
+
+print(result)
+
+print(result.dtypes)
+
+expected = pd.DataFrame(
+    {
+        "id": pd.Series([5.0, 4.0, None, 2.0], dtype="object"),
+        "col": cat_series,
+    }
+)
+
+pd.testing.assert_frame_equal(result, expected)