projektAI/venv/Lib/site-packages/pandas/tests/indexing/multiindex/test_chaining_and_caching.py
2021-06-06 22:13:05 +02:00

67 lines
2.0 KiB
Python

import numpy as np
import pytest
from pandas import DataFrame, MultiIndex, Series
import pandas._testing as tm
import pandas.core.common as com
def test_detect_chained_assignment():
# Inplace ops, originally from:
# https://stackoverflow.com/questions/20508968/series-fillna-in-a-multiindex-dataframe-does-not-fill-is-this-a-bug
a = [12, 23]
b = [123, None]
c = [1234, 2345]
d = [12345, 23456]
tuples = [("eyes", "left"), ("eyes", "right"), ("ears", "left"), ("ears", "right")]
events = {
("eyes", "left"): a,
("eyes", "right"): b,
("ears", "left"): c,
("ears", "right"): d,
}
multiind = MultiIndex.from_tuples(tuples, names=["part", "side"])
zed = DataFrame(events, index=["a", "b"], columns=multiind)
msg = "A value is trying to be set on a copy of a slice from a DataFrame"
with pytest.raises(com.SettingWithCopyError, match=msg):
zed["eyes"]["right"].fillna(value=555, inplace=True)
def test_cache_updating():
# 5216
# make sure that we don't try to set a dead cache
a = np.random.rand(10, 3)
df = DataFrame(a, columns=["x", "y", "z"])
tuples = [(i, j) for i in range(5) for j in range(2)]
index = MultiIndex.from_tuples(tuples)
df.index = index
# setting via chained assignment
# but actually works, since everything is a view
df.loc[0]["z"].iloc[0] = 1.0
result = df.loc[(0, 0), "z"]
assert result == 1
# correct setting
df.loc[(0, 0), "z"] = 2
result = df.loc[(0, 0), "z"]
assert result == 2
@pytest.mark.arm_slow
def test_indexer_caching():
# GH5727
# make sure that indexers are in the _internal_names_set
n = 1000001
arrays = (range(n), range(n))
index = MultiIndex.from_tuples(zip(*arrays))
s = Series(np.zeros(n), index=index)
str(s)
# setitem
expected = Series(np.ones(n), index=index)
s = Series(np.zeros(n), index=index)
s[s == 0] = 1
tm.assert_series_equal(s, expected)