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import numpy as np
import pandas as pd
from pandas import (
DataFrame,
Index,
)
import pandas._testing as tm
def test_pipe():
# Test the pipe method of DataFrameGroupBy.
# Issue #17871
random_state = np.random.default_rng(2)
df = DataFrame(
{
"A": ["foo", "bar", "foo", "bar", "foo", "bar", "foo", "foo"],
"B": random_state.standard_normal(8),
"C": random_state.standard_normal(8),
}
)
def f(dfgb):
return dfgb.B.max() - dfgb.C.min().min()
def square(srs):
return srs**2
# Note that the transformations are
# GroupBy -> Series
# Series -> Series
# This then chains the GroupBy.pipe and the
# NDFrame.pipe methods
result = df.groupby("A").pipe(f).pipe(square)
index = Index(["bar", "foo"], dtype="object", name="A")
expected = pd.Series([3.749306591013693, 6.717707873081384], name="B", index=index)
tm.assert_series_equal(expected, result)
def test_pipe_args():
# Test passing args to the pipe method of DataFrameGroupBy.
# Issue #17871
df = DataFrame(
{
"group": ["A", "A", "B", "B", "C"],
"x": [1.0, 2.0, 3.0, 2.0, 5.0],
"y": [10.0, 100.0, 1000.0, -100.0, -1000.0],
}
)
def f(dfgb, arg1):
filtered = dfgb.filter(lambda grp: grp.y.mean() > arg1, dropna=False)
return filtered.groupby("group")
def g(dfgb, arg2):
return dfgb.sum() / dfgb.sum().sum() + arg2
def h(df, arg3):
return df.x + df.y - arg3
result = df.groupby("group").pipe(f, 0).pipe(g, 10).pipe(h, 100)
# Assert the results here
index = Index(["A", "B"], name="group")
expected = pd.Series([-79.5160891089, -78.4839108911], index=index)
tm.assert_series_equal(result, expected)
# test SeriesGroupby.pipe
ser = pd.Series([1, 1, 2, 2, 3, 3])
result = ser.groupby(ser).pipe(lambda grp: grp.sum() * grp.count())
expected = pd.Series([4, 8, 12], index=Index([1, 2, 3], dtype=np.int64))
tm.assert_series_equal(result, expected)