ai-content-maker/.venv/Lib/site-packages/pandas/tests/frame/methods/test_shift.py

692 lines
24 KiB
Python

import numpy as np
import pytest
import pandas.util._test_decorators as td
import pandas as pd
from pandas import (
CategoricalIndex,
DataFrame,
Index,
NaT,
Series,
date_range,
offsets,
)
import pandas._testing as tm
class TestDataFrameShift:
@pytest.mark.parametrize(
"input_data, output_data",
[(np.empty(shape=(0,)), []), (np.ones(shape=(2,)), [np.nan, 1.0])],
)
def test_shift_non_writable_array(self, input_data, output_data, frame_or_series):
# GH21049 Verify whether non writable numpy array is shiftable
input_data.setflags(write=False)
result = frame_or_series(input_data).shift(1)
if frame_or_series is not Series:
# need to explicitly specify columns in the empty case
expected = frame_or_series(
output_data,
index=range(len(output_data)),
columns=range(1),
dtype="float64",
)
else:
expected = frame_or_series(output_data, dtype="float64")
tm.assert_equal(result, expected)
def test_shift_mismatched_freq(self, frame_or_series):
ts = frame_or_series(
np.random.randn(5), index=date_range("1/1/2000", periods=5, freq="H")
)
result = ts.shift(1, freq="5T")
exp_index = ts.index.shift(1, freq="5T")
tm.assert_index_equal(result.index, exp_index)
# GH#1063, multiple of same base
result = ts.shift(1, freq="4H")
exp_index = ts.index + offsets.Hour(4)
tm.assert_index_equal(result.index, exp_index)
@pytest.mark.parametrize(
"obj",
[
Series([np.arange(5)]),
date_range("1/1/2011", periods=24, freq="H"),
Series(range(5), index=date_range("2017", periods=5)),
],
)
@pytest.mark.parametrize("shift_size", [0, 1, 2])
def test_shift_always_copy(self, obj, shift_size, frame_or_series):
# GH#22397
if frame_or_series is not Series:
obj = obj.to_frame()
assert obj.shift(shift_size) is not obj
def test_shift_object_non_scalar_fill(self):
# shift requires scalar fill_value except for object dtype
ser = Series(range(3))
with pytest.raises(ValueError, match="fill_value must be a scalar"):
ser.shift(1, fill_value=[])
df = ser.to_frame()
with pytest.raises(ValueError, match="fill_value must be a scalar"):
df.shift(1, fill_value=np.arange(3))
obj_ser = ser.astype(object)
result = obj_ser.shift(1, fill_value={})
assert result[0] == {}
obj_df = obj_ser.to_frame()
result = obj_df.shift(1, fill_value={})
assert result.iloc[0, 0] == {}
def test_shift_int(self, datetime_frame, frame_or_series):
ts = tm.get_obj(datetime_frame, frame_or_series).astype(int)
shifted = ts.shift(1)
expected = ts.astype(float).shift(1)
tm.assert_equal(shifted, expected)
@pytest.mark.parametrize("dtype", ["int32", "int64"])
def test_shift_32bit_take(self, frame_or_series, dtype):
# 32-bit taking
# GH#8129
index = date_range("2000-01-01", periods=5)
arr = np.arange(5, dtype=dtype)
s1 = frame_or_series(arr, index=index)
p = arr[1]
result = s1.shift(periods=p)
expected = frame_or_series([np.nan, 0, 1, 2, 3], index=index)
tm.assert_equal(result, expected)
@pytest.mark.parametrize("periods", [1, 2, 3, 4])
def test_shift_preserve_freqstr(self, periods, frame_or_series):
# GH#21275
obj = frame_or_series(
range(periods),
index=date_range("2016-1-1 00:00:00", periods=periods, freq="H"),
)
result = obj.shift(1, "2H")
expected = frame_or_series(
range(periods),
index=date_range("2016-1-1 02:00:00", periods=periods, freq="H"),
)
tm.assert_equal(result, expected)
def test_shift_dst(self, frame_or_series):
# GH#13926
dates = date_range("2016-11-06", freq="H", periods=10, tz="US/Eastern")
obj = frame_or_series(dates)
res = obj.shift(0)
tm.assert_equal(res, obj)
assert tm.get_dtype(res) == "datetime64[ns, US/Eastern]"
res = obj.shift(1)
exp_vals = [NaT] + dates.astype(object).values.tolist()[:9]
exp = frame_or_series(exp_vals)
tm.assert_equal(res, exp)
assert tm.get_dtype(res) == "datetime64[ns, US/Eastern]"
res = obj.shift(-2)
exp_vals = dates.astype(object).values.tolist()[2:] + [NaT, NaT]
exp = frame_or_series(exp_vals)
tm.assert_equal(res, exp)
assert tm.get_dtype(res) == "datetime64[ns, US/Eastern]"
@pytest.mark.parametrize("ex", [10, -10, 20, -20])
def test_shift_dst_beyond(self, frame_or_series, ex):
# GH#13926
dates = date_range("2016-11-06", freq="H", periods=10, tz="US/Eastern")
obj = frame_or_series(dates)
res = obj.shift(ex)
exp = frame_or_series([NaT] * 10, dtype="datetime64[ns, US/Eastern]")
tm.assert_equal(res, exp)
assert tm.get_dtype(res) == "datetime64[ns, US/Eastern]"
def test_shift_by_zero(self, datetime_frame, frame_or_series):
# shift by 0
obj = tm.get_obj(datetime_frame, frame_or_series)
unshifted = obj.shift(0)
tm.assert_equal(unshifted, obj)
def test_shift(self, datetime_frame):
# naive shift
ser = datetime_frame["A"]
shifted = datetime_frame.shift(5)
tm.assert_index_equal(shifted.index, datetime_frame.index)
shifted_ser = ser.shift(5)
tm.assert_series_equal(shifted["A"], shifted_ser)
shifted = datetime_frame.shift(-5)
tm.assert_index_equal(shifted.index, datetime_frame.index)
shifted_ser = ser.shift(-5)
tm.assert_series_equal(shifted["A"], shifted_ser)
unshifted = datetime_frame.shift(5).shift(-5)
tm.assert_numpy_array_equal(
unshifted.dropna().values, datetime_frame.values[:-5]
)
unshifted_ser = ser.shift(5).shift(-5)
tm.assert_numpy_array_equal(unshifted_ser.dropna().values, ser.values[:-5])
def test_shift_by_offset(self, datetime_frame, frame_or_series):
# shift by DateOffset
obj = tm.get_obj(datetime_frame, frame_or_series)
offset = offsets.BDay()
shifted = obj.shift(5, freq=offset)
assert len(shifted) == len(obj)
unshifted = shifted.shift(-5, freq=offset)
tm.assert_equal(unshifted, obj)
shifted2 = obj.shift(5, freq="B")
tm.assert_equal(shifted, shifted2)
unshifted = obj.shift(0, freq=offset)
tm.assert_equal(unshifted, obj)
d = obj.index[0]
shifted_d = d + offset * 5
if frame_or_series is DataFrame:
tm.assert_series_equal(obj.xs(d), shifted.xs(shifted_d), check_names=False)
else:
tm.assert_almost_equal(obj.at[d], shifted.at[shifted_d])
def test_shift_with_periodindex(self, frame_or_series):
# Shifting with PeriodIndex
ps = tm.makePeriodFrame()
ps = tm.get_obj(ps, frame_or_series)
shifted = ps.shift(1)
unshifted = shifted.shift(-1)
tm.assert_index_equal(shifted.index, ps.index)
tm.assert_index_equal(unshifted.index, ps.index)
if frame_or_series is DataFrame:
tm.assert_numpy_array_equal(
unshifted.iloc[:, 0].dropna().values, ps.iloc[:-1, 0].values
)
else:
tm.assert_numpy_array_equal(unshifted.dropna().values, ps.values[:-1])
shifted2 = ps.shift(1, "B")
shifted3 = ps.shift(1, offsets.BDay())
tm.assert_equal(shifted2, shifted3)
tm.assert_equal(ps, shifted2.shift(-1, "B"))
msg = "does not match PeriodIndex freq"
with pytest.raises(ValueError, match=msg):
ps.shift(freq="D")
# legacy support
shifted4 = ps.shift(1, freq="B")
tm.assert_equal(shifted2, shifted4)
shifted5 = ps.shift(1, freq=offsets.BDay())
tm.assert_equal(shifted5, shifted4)
def test_shift_other_axis(self):
# shift other axis
# GH#6371
df = DataFrame(np.random.rand(10, 5))
expected = pd.concat(
[DataFrame(np.nan, index=df.index, columns=[0]), df.iloc[:, 0:-1]],
ignore_index=True,
axis=1,
)
result = df.shift(1, axis=1)
tm.assert_frame_equal(result, expected)
def test_shift_named_axis(self):
# shift named axis
df = DataFrame(np.random.rand(10, 5))
expected = pd.concat(
[DataFrame(np.nan, index=df.index, columns=[0]), df.iloc[:, 0:-1]],
ignore_index=True,
axis=1,
)
result = df.shift(1, axis="columns")
tm.assert_frame_equal(result, expected)
def test_shift_other_axis_with_freq(self, datetime_frame):
obj = datetime_frame.T
offset = offsets.BDay()
# GH#47039
shifted = obj.shift(5, freq=offset, axis=1)
assert len(shifted) == len(obj)
unshifted = shifted.shift(-5, freq=offset, axis=1)
tm.assert_equal(unshifted, obj)
def test_shift_bool(self):
df = DataFrame({"high": [True, False], "low": [False, False]})
rs = df.shift(1)
xp = DataFrame(
np.array([[np.nan, np.nan], [True, False]], dtype=object),
columns=["high", "low"],
)
tm.assert_frame_equal(rs, xp)
def test_shift_categorical1(self, frame_or_series):
# GH#9416
obj = frame_or_series(["a", "b", "c", "d"], dtype="category")
rt = obj.shift(1).shift(-1)
tm.assert_equal(obj.iloc[:-1], rt.dropna())
def get_cat_values(ndframe):
# For Series we could just do ._values; for DataFrame
# we may be able to do this if we ever have 2D Categoricals
return ndframe._mgr.arrays[0]
cat = get_cat_values(obj)
sp1 = obj.shift(1)
tm.assert_index_equal(obj.index, sp1.index)
assert np.all(get_cat_values(sp1).codes[:1] == -1)
assert np.all(cat.codes[:-1] == get_cat_values(sp1).codes[1:])
sn2 = obj.shift(-2)
tm.assert_index_equal(obj.index, sn2.index)
assert np.all(get_cat_values(sn2).codes[-2:] == -1)
assert np.all(cat.codes[2:] == get_cat_values(sn2).codes[:-2])
tm.assert_index_equal(cat.categories, get_cat_values(sp1).categories)
tm.assert_index_equal(cat.categories, get_cat_values(sn2).categories)
def test_shift_categorical(self):
# GH#9416
s1 = Series(["a", "b", "c"], dtype="category")
s2 = Series(["A", "B", "C"], dtype="category")
df = DataFrame({"one": s1, "two": s2})
rs = df.shift(1)
xp = DataFrame({"one": s1.shift(1), "two": s2.shift(1)})
tm.assert_frame_equal(rs, xp)
def test_shift_categorical_fill_value(self, frame_or_series):
ts = frame_or_series(["a", "b", "c", "d"], dtype="category")
res = ts.shift(1, fill_value="a")
expected = frame_or_series(
pd.Categorical(
["a", "a", "b", "c"], categories=["a", "b", "c", "d"], ordered=False
)
)
tm.assert_equal(res, expected)
# check for incorrect fill_value
msg = r"Cannot setitem on a Categorical with a new category \(f\)"
with pytest.raises(TypeError, match=msg):
ts.shift(1, fill_value="f")
def test_shift_fill_value(self, frame_or_series):
# GH#24128
dti = date_range("1/1/2000", periods=5, freq="H")
ts = frame_or_series([1.0, 2.0, 3.0, 4.0, 5.0], index=dti)
exp = frame_or_series([0.0, 1.0, 2.0, 3.0, 4.0], index=dti)
# check that fill value works
result = ts.shift(1, fill_value=0.0)
tm.assert_equal(result, exp)
exp = frame_or_series([0.0, 0.0, 1.0, 2.0, 3.0], index=dti)
result = ts.shift(2, fill_value=0.0)
tm.assert_equal(result, exp)
ts = frame_or_series([1, 2, 3])
res = ts.shift(2, fill_value=0)
assert tm.get_dtype(res) == tm.get_dtype(ts)
# retain integer dtype
obj = frame_or_series([1, 2, 3, 4, 5], index=dti)
exp = frame_or_series([0, 1, 2, 3, 4], index=dti)
result = obj.shift(1, fill_value=0)
tm.assert_equal(result, exp)
exp = frame_or_series([0, 0, 1, 2, 3], index=dti)
result = obj.shift(2, fill_value=0)
tm.assert_equal(result, exp)
def test_shift_empty(self):
# Regression test for GH#8019
df = DataFrame({"foo": []})
rs = df.shift(-1)
tm.assert_frame_equal(df, rs)
def test_shift_duplicate_columns(self, using_array_manager):
# GH#9092; verify that position-based shifting works
# in the presence of duplicate columns
column_lists = [list(range(5)), [1] * 5, [1, 1, 2, 2, 1]]
data = np.random.randn(20, 5)
warn = None
if using_array_manager:
warn = DeprecationWarning
shifted = []
for columns in column_lists:
df = DataFrame(data.copy(), columns=columns)
for s in range(5):
msg = "will attempt to set the values inplace"
with tm.assert_produces_warning(warn, match=msg):
df.iloc[:, s] = df.iloc[:, s].shift(s + 1)
df.columns = range(5)
shifted.append(df)
# sanity check the base case
nulls = shifted[0].isna().sum()
tm.assert_series_equal(nulls, Series(range(1, 6), dtype="int64"))
# check all answers are the same
tm.assert_frame_equal(shifted[0], shifted[1])
tm.assert_frame_equal(shifted[0], shifted[2])
def test_shift_axis1_multiple_blocks(self, using_array_manager):
# GH#35488
df1 = DataFrame(np.random.randint(1000, size=(5, 3)))
df2 = DataFrame(np.random.randint(1000, size=(5, 2)))
df3 = pd.concat([df1, df2], axis=1)
if not using_array_manager:
assert len(df3._mgr.blocks) == 2
result = df3.shift(2, axis=1)
expected = df3.take([-1, -1, 0, 1, 2], axis=1)
expected.iloc[:, :2] = np.nan
expected.columns = df3.columns
tm.assert_frame_equal(result, expected)
# Case with periods < 0
# rebuild df3 because `take` call above consolidated
df3 = pd.concat([df1, df2], axis=1)
if not using_array_manager:
assert len(df3._mgr.blocks) == 2
result = df3.shift(-2, axis=1)
expected = df3.take([2, 3, 4, -1, -1], axis=1)
expected.iloc[:, -2:] = np.nan
expected.columns = df3.columns
tm.assert_frame_equal(result, expected)
@td.skip_array_manager_not_yet_implemented # TODO(ArrayManager) axis=1 support
def test_shift_axis1_multiple_blocks_with_int_fill(self):
# GH#42719
df1 = DataFrame(np.random.randint(1000, size=(5, 3)))
df2 = DataFrame(np.random.randint(1000, size=(5, 2)))
df3 = pd.concat([df1.iloc[:4, 1:3], df2.iloc[:4, :]], axis=1)
result = df3.shift(2, axis=1, fill_value=np.int_(0))
assert len(df3._mgr.blocks) == 2
expected = df3.take([-1, -1, 0, 1], axis=1)
expected.iloc[:, :2] = np.int_(0)
expected.columns = df3.columns
tm.assert_frame_equal(result, expected)
# Case with periods < 0
df3 = pd.concat([df1.iloc[:4, 1:3], df2.iloc[:4, :]], axis=1)
result = df3.shift(-2, axis=1, fill_value=np.int_(0))
assert len(df3._mgr.blocks) == 2
expected = df3.take([2, 3, -1, -1], axis=1)
expected.iloc[:, -2:] = np.int_(0)
expected.columns = df3.columns
tm.assert_frame_equal(result, expected)
@pytest.mark.filterwarnings("ignore:tshift is deprecated:FutureWarning")
def test_tshift(self, datetime_frame, frame_or_series):
# TODO(2.0): remove this test when tshift deprecation is enforced
# PeriodIndex
ps = tm.makePeriodFrame()
ps = tm.get_obj(ps, frame_or_series)
shifted = ps.tshift(1)
unshifted = shifted.tshift(-1)
tm.assert_equal(unshifted, ps)
shifted2 = ps.tshift(freq="B")
tm.assert_equal(shifted, shifted2)
shifted3 = ps.tshift(freq=offsets.BDay())
tm.assert_equal(shifted, shifted3)
msg = "Given freq M does not match PeriodIndex freq B"
with pytest.raises(ValueError, match=msg):
ps.tshift(freq="M")
# DatetimeIndex
dtobj = tm.get_obj(datetime_frame, frame_or_series)
shifted = dtobj.tshift(1)
unshifted = shifted.tshift(-1)
tm.assert_equal(dtobj, unshifted)
shifted2 = dtobj.tshift(freq=dtobj.index.freq)
tm.assert_equal(shifted, shifted2)
inferred_ts = DataFrame(
datetime_frame.values,
Index(np.asarray(datetime_frame.index)),
columns=datetime_frame.columns,
)
inferred_ts = tm.get_obj(inferred_ts, frame_or_series)
shifted = inferred_ts.tshift(1)
expected = dtobj.tshift(1)
expected.index = expected.index._with_freq(None)
tm.assert_equal(shifted, expected)
unshifted = shifted.tshift(-1)
tm.assert_equal(unshifted, inferred_ts)
no_freq = dtobj.iloc[[0, 5, 7]]
msg = "Freq was not set in the index hence cannot be inferred"
with pytest.raises(ValueError, match=msg):
no_freq.tshift()
def test_tshift_deprecated(self, datetime_frame, frame_or_series):
# GH#11631
dtobj = tm.get_obj(datetime_frame, frame_or_series)
with tm.assert_produces_warning(FutureWarning):
dtobj.tshift()
def test_period_index_frame_shift_with_freq(self, frame_or_series):
ps = tm.makePeriodFrame()
ps = tm.get_obj(ps, frame_or_series)
shifted = ps.shift(1, freq="infer")
unshifted = shifted.shift(-1, freq="infer")
tm.assert_equal(unshifted, ps)
shifted2 = ps.shift(freq="B")
tm.assert_equal(shifted, shifted2)
shifted3 = ps.shift(freq=offsets.BDay())
tm.assert_equal(shifted, shifted3)
def test_datetime_frame_shift_with_freq(self, datetime_frame, frame_or_series):
dtobj = tm.get_obj(datetime_frame, frame_or_series)
shifted = dtobj.shift(1, freq="infer")
unshifted = shifted.shift(-1, freq="infer")
tm.assert_equal(dtobj, unshifted)
shifted2 = dtobj.shift(freq=dtobj.index.freq)
tm.assert_equal(shifted, shifted2)
inferred_ts = DataFrame(
datetime_frame.values,
Index(np.asarray(datetime_frame.index)),
columns=datetime_frame.columns,
)
inferred_ts = tm.get_obj(inferred_ts, frame_or_series)
shifted = inferred_ts.shift(1, freq="infer")
expected = dtobj.shift(1, freq="infer")
expected.index = expected.index._with_freq(None)
tm.assert_equal(shifted, expected)
unshifted = shifted.shift(-1, freq="infer")
tm.assert_equal(unshifted, inferred_ts)
def test_period_index_frame_shift_with_freq_error(self, frame_or_series):
ps = tm.makePeriodFrame()
ps = tm.get_obj(ps, frame_or_series)
msg = "Given freq M does not match PeriodIndex freq B"
with pytest.raises(ValueError, match=msg):
ps.shift(freq="M")
def test_datetime_frame_shift_with_freq_error(
self, datetime_frame, frame_or_series
):
dtobj = tm.get_obj(datetime_frame, frame_or_series)
no_freq = dtobj.iloc[[0, 5, 7]]
msg = "Freq was not set in the index hence cannot be inferred"
with pytest.raises(ValueError, match=msg):
no_freq.shift(freq="infer")
@td.skip_array_manager_not_yet_implemented # TODO(ArrayManager) axis=1 support
def test_shift_dt64values_int_fill_deprecated(self):
# GH#31971
ser = Series([pd.Timestamp("2020-01-01"), pd.Timestamp("2020-01-02")])
with tm.assert_produces_warning(FutureWarning):
result = ser.shift(1, fill_value=0)
expected = Series([pd.Timestamp(0), ser[0]])
tm.assert_series_equal(result, expected)
df = ser.to_frame()
with tm.assert_produces_warning(FutureWarning):
result = df.shift(1, fill_value=0)
expected = expected.to_frame()
tm.assert_frame_equal(result, expected)
# axis = 1
df2 = DataFrame({"A": ser, "B": ser})
df2._consolidate_inplace()
with tm.assert_produces_warning(FutureWarning):
result = df2.shift(1, axis=1, fill_value=0)
expected = DataFrame({"A": [pd.Timestamp(0), pd.Timestamp(0)], "B": df2["A"]})
tm.assert_frame_equal(result, expected)
# same thing but not consolidated
# This isn't great that we get different behavior, but
# that will go away when the deprecation is enforced
df3 = DataFrame({"A": ser})
df3["B"] = ser
assert len(df3._mgr.arrays) == 2
result = df3.shift(1, axis=1, fill_value=0)
expected = DataFrame({"A": [0, 0], "B": df2["A"]})
tm.assert_frame_equal(result, expected)
@pytest.mark.parametrize(
"as_cat",
[
pytest.param(
True,
marks=pytest.mark.xfail(
reason="_can_hold_element incorrectly always returns True"
),
),
False,
],
)
@pytest.mark.parametrize(
"vals",
[
date_range("2020-01-01", periods=2),
date_range("2020-01-01", periods=2, tz="US/Pacific"),
pd.period_range("2020-01-01", periods=2, freq="D"),
pd.timedelta_range("2020 Days", periods=2, freq="D"),
pd.interval_range(0, 3, periods=2),
pytest.param(
pd.array([1, 2], dtype="Int64"),
marks=pytest.mark.xfail(
reason="_can_hold_element incorrectly always returns True"
),
),
pytest.param(
pd.array([1, 2], dtype="Float32"),
marks=pytest.mark.xfail(
reason="_can_hold_element incorrectly always returns True"
),
),
],
ids=lambda x: str(x.dtype),
)
# TODO(2.0): remove filtering
@pytest.mark.filterwarnings("ignore:Index.ravel.*:FutureWarning")
def test_shift_dt64values_axis1_invalid_fill(self, vals, as_cat):
# GH#44564
ser = Series(vals)
if as_cat:
ser = ser.astype("category")
df = DataFrame({"A": ser})
result = df.shift(-1, axis=1, fill_value="foo")
expected = DataFrame({"A": ["foo", "foo"]})
tm.assert_frame_equal(result, expected)
# same thing but multiple blocks
df2 = DataFrame({"A": ser, "B": ser})
df2._consolidate_inplace()
result = df2.shift(-1, axis=1, fill_value="foo")
expected = DataFrame({"A": df2["B"], "B": ["foo", "foo"]})
tm.assert_frame_equal(result, expected)
# same thing but not consolidated
df3 = DataFrame({"A": ser})
df3["B"] = ser
assert len(df3._mgr.arrays) == 2
result = df3.shift(-1, axis=1, fill_value="foo")
tm.assert_frame_equal(result, expected)
def test_shift_axis1_categorical_columns(self):
# GH#38434
ci = CategoricalIndex(["a", "b", "c"])
df = DataFrame(
{"a": [1, 3], "b": [2, 4], "c": [5, 6]}, index=ci[:-1], columns=ci
)
result = df.shift(axis=1)
expected = DataFrame(
{"a": [np.nan, np.nan], "b": [1, 3], "c": [2, 4]}, index=ci[:-1], columns=ci
)
tm.assert_frame_equal(result, expected)
# periods != 1
result = df.shift(2, axis=1)
expected = DataFrame(
{"a": [np.nan, np.nan], "b": [np.nan, np.nan], "c": [1, 3]},
index=ci[:-1],
columns=ci,
)
tm.assert_frame_equal(result, expected)
def test_shift_axis1_many_periods(self):
# GH#44978 periods > len(columns)
df = DataFrame(np.random.rand(5, 3))
shifted = df.shift(6, axis=1, fill_value=None)
expected = df * np.nan
tm.assert_frame_equal(shifted, expected)
shifted2 = df.shift(-6, axis=1, fill_value=None)
tm.assert_frame_equal(shifted2, expected)