GroupBy.apply: `error: No overloads for "apply" match the provided arguments (reportCallIssue)`

[schorlton-bugseq]

To Reproduce

import pandas as pd

df = pd.DataFrame({
    "group": ["A", "A", "B", "B", "C"],
    "value": [10, 15, 10, 25, 30]
})


def add_constant_to_mean(group: pd.DataFrame, constant: int) -> pd.DataFrame:
    mean_val = group["value"].mean()
    group["adjusted"] = mean_val + constant
    return group

result = df.groupby("group", group_keys=False).apply(add_constant_to_mean, constant=5)

Linting using pyright (version 1.1.393) and pandas-stubs 2.2.3.250527:

error: No overloads for "apply" match the provided arguments (reportCallIssue)

Thanks!!

[Dr-Irv]

Thanks for the report. Am creating a PR using Protocol to fix this.

[Dr-Irv]

Note: The code above does produce a FutureWarning, so I changed the test to

df.groupby("group", group_keys=False)[["group", "value"]].apply(
                add_constant_to_mean, constant=5
            )