sample `pandas` operations affected by function-call penalty

sample.py

from pandas import Series
from numpy.random import default_rng
from string import ascii_lowercase

rng = default_rng(0)

s = Series(
    rng.integers(-10, 10, size=(size := 10_000)),
    index=rng.choice([*ascii_lowercase], size=(size, length := 10)).view(f'<U{length}').ravel(),
)

def udf(col):
    ''' sample user-defined function '''
    return 0

# will call `udf` once per unique group
s.groupby(s.index).aggregate(udf)

# will call `udf` once per three rows
s.rolling(3).aggregate(udf)

# will call `udf` once per row
s.expanding().aggregate(udf)