ENH: pd.concat with keys and ignore_index=True should raise · Issue #59274 · pandas-dev/pandas (original) (raw)

Feature Type

• Adding new functionality to pandas
• Changing existing functionality in pandas
• Removing existing functionality in pandas

Problem Description

You can happily pass both of these arguments together, but the ignore_index=True call drops the keys, so it ends up being a moot point:

In [1]: import pandas as pd

In [2]: df1 = pd.DataFrame([[0]])

In [3]: df2 = pd.DataFrame([[42]])

In [4]: pd.concat([df1, df2]) Out[4]: 0 0 0 0 42

In [5]: pd.concat([df1, df2], keys=["df1", "df2"]) Out[5]: 0 df1 0 0 df2 0 42

In [6]: pd.concat([df1, df2], keys=["df1", "df2"], ignore_index=True) Out[6]: 0 0 0 1 42

Feature Description

pandas can raise that this combination of values does not make sense

Alternative Solutions

status quo

Additional Context

No response