BUG: GroupBy Aggregation Behavior

[clampr]

• I have asked my usage related question on StackOverflow.

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Question About GroupBy Aggregation Behavior

I observed a behavior of the Pandas GroupBy method agg() which I cannot explain based on the docs.

I want to perform a custom aggregation on a grouped DataFrame. Let's take this code snippet:

def aggregate_point(x):
 print(x)
 exit()

data = data.groupby(
 pd.Grouper(level='time', freq='1H')).agg(aggregate_point)

This prints a Series for each group.

However, when I pass any additional parameter to aggregate_point, the full DataFrame is being printed:

def aggregate_point(x, score):
 print(x)
 exit()

data = data.groupby(
 pd.Grouper(level='time', freq='1H')).agg(aggregate_point, score=True)

Why does the score parameter influence the value of x (DataFrame vs. Series)?

[rhshadrach]

This is a bug, related to #39169. The addition of a parameter should not have this influence.

[jnchngc]

take

[mroeschke]

Closing at this appears identical to #39169