BUG: incompatible dtype when creating string column with loc · Issue #55025 · pandas-dev/pandas (original) (raw)

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Reproducible Example

import pandas as pd df = pd.DataFrame({"x": [1]}) df.loc[df["x"] == 1, "y"] = "1"

Issue Description

I get a FutureWarning when conditionally creating a new string column in loc.

It does not happen if the column is numeric, assumably because float64 is the default dtype.

The warning dissappears when setting the column to NA beforehand, but I assume this is not meant as a nessecary additional step for non-numeric columns only.

FutureWarning: Setting an item of incompatible dtype is deprecated and will raise in a future error of pandas. Value '1' has dtype incompatible with float64, please explicitly cast to a compatible dtype first.
df.loc[df["x"] == 1, "y"] = "1"

Expected Behavior

No warning.

Installed Versions

2.1.0