import numpy as np
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import pytest
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import pandas as pd
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from pandas import (
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DataFrame,
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Series,
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Timestamp,
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date_range,
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)
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import pandas._testing as tm
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class TestDataFrameDiff:
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def test_diff_requires_integer(self):
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df = DataFrame(np.random.randn(2, 2))
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with pytest.raises(ValueError, match="periods must be an integer"):
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df.diff(1.5)
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# GH#44572 np.int64 is accepted
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@pytest.mark.parametrize("num", [1, np.int64(1)])
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def test_diff(self, datetime_frame, num):
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df = datetime_frame
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the_diff = df.diff(num)
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expected = df["A"] - df["A"].shift(num)
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tm.assert_series_equal(the_diff["A"], expected)
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def test_diff_int_dtype(self):
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# int dtype
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a = 10_000_000_000_000_000
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b = a + 1
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ser = Series([a, b])
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rs = DataFrame({"s": ser}).diff()
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assert rs.s[1] == 1
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def test_diff_mixed_numeric(self, datetime_frame):
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# mixed numeric
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tf = datetime_frame.astype("float32")
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the_diff = tf.diff(1)
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tm.assert_series_equal(the_diff["A"], tf["A"] - tf["A"].shift(1))
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def test_diff_axis1_nonconsolidated(self):
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# GH#10907
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df = DataFrame({"y": Series([2]), "z": Series([3])})
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df.insert(0, "x", 1)
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result = df.diff(axis=1)
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expected = DataFrame({"x": np.nan, "y": Series(1), "z": Series(1)})
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tm.assert_frame_equal(result, expected)
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def test_diff_timedelta64_with_nat(self):
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# GH#32441
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arr = np.arange(6).reshape(3, 2).astype("timedelta64[ns]")
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arr[:, 0] = np.timedelta64("NaT", "ns")
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df = DataFrame(arr)
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result = df.diff(1, axis=0)
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expected = DataFrame({0: df[0], 1: [pd.NaT, pd.Timedelta(2), pd.Timedelta(2)]})
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tm.assert_equal(result, expected)
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result = df.diff(0)
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expected = df - df
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assert expected[0].isna().all()
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tm.assert_equal(result, expected)
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result = df.diff(-1, axis=1)
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expected = df * np.nan
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tm.assert_equal(result, expected)
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@pytest.mark.parametrize("tz", [None, "UTC"])
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def test_diff_datetime_axis0_with_nat(self, tz):
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# GH#32441
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dti = pd.DatetimeIndex(["NaT", "2019-01-01", "2019-01-02"], tz=tz)
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ser = Series(dti)
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df = ser.to_frame()
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result = df.diff()
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ex_index = pd.TimedeltaIndex([pd.NaT, pd.NaT, pd.Timedelta(days=1)])
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expected = Series(ex_index).to_frame()
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize("tz", [None, "UTC"])
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def test_diff_datetime_with_nat_zero_periods(self, tz):
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# diff on NaT values should give NaT, not timedelta64(0)
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dti = date_range("2016-01-01", periods=4, tz=tz)
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ser = Series(dti)
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df = ser.to_frame()
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df[1] = ser.copy()
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df.iloc[:, 0] = pd.NaT
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expected = df - df
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assert expected[0].isna().all()
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result = df.diff(0, axis=0)
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tm.assert_frame_equal(result, expected)
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result = df.diff(0, axis=1)
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize("tz", [None, "UTC"])
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def test_diff_datetime_axis0(self, tz):
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# GH#18578
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df = DataFrame(
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{
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0: date_range("2010", freq="D", periods=2, tz=tz),
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1: date_range("2010", freq="D", periods=2, tz=tz),
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}
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)
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result = df.diff(axis=0)
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expected = DataFrame(
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{
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0: pd.TimedeltaIndex(["NaT", "1 days"]),
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1: pd.TimedeltaIndex(["NaT", "1 days"]),
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}
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)
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize("tz", [None, "UTC"])
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def test_diff_datetime_axis1(self, tz):
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# GH#18578
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df = DataFrame(
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{
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0: date_range("2010", freq="D", periods=2, tz=tz),
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1: date_range("2010", freq="D", periods=2, tz=tz),
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}
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)
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result = df.diff(axis=1)
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expected = DataFrame(
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{
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0: pd.TimedeltaIndex(["NaT", "NaT"]),
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1: pd.TimedeltaIndex(["0 days", "0 days"]),
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}
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)
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tm.assert_frame_equal(result, expected)
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def test_diff_timedelta(self):
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# GH#4533
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df = DataFrame(
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{
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"time": [Timestamp("20130101 9:01"), Timestamp("20130101 9:02")],
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"value": [1.0, 2.0],
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}
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)
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res = df.diff()
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exp = DataFrame(
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[[pd.NaT, np.nan], [pd.Timedelta("00:01:00"), 1]], columns=["time", "value"]
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)
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tm.assert_frame_equal(res, exp)
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def test_diff_mixed_dtype(self):
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df = DataFrame(np.random.randn(5, 3))
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df["A"] = np.array([1, 2, 3, 4, 5], dtype=object)
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result = df.diff()
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assert result[0].dtype == np.float64
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def test_diff_neg_n(self, datetime_frame):
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rs = datetime_frame.diff(-1)
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xp = datetime_frame - datetime_frame.shift(-1)
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tm.assert_frame_equal(rs, xp)
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def test_diff_float_n(self, datetime_frame):
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rs = datetime_frame.diff(1.0)
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xp = datetime_frame.diff(1)
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tm.assert_frame_equal(rs, xp)
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def test_diff_axis(self):
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# GH#9727
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df = DataFrame([[1.0, 2.0], [3.0, 4.0]])
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tm.assert_frame_equal(
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df.diff(axis=1), DataFrame([[np.nan, 1.0], [np.nan, 1.0]])
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)
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tm.assert_frame_equal(
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df.diff(axis=0), DataFrame([[np.nan, np.nan], [2.0, 2.0]])
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)
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def test_diff_period(self):
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# GH#32995 Don't pass an incorrect axis
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pi = date_range("2016-01-01", periods=3).to_period("D")
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df = DataFrame({"A": pi})
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result = df.diff(1, axis=1)
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expected = (df - pd.NaT).astype(object)
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tm.assert_frame_equal(result, expected)
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def test_diff_axis1_mixed_dtypes(self):
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# GH#32995 operate column-wise when we have mixed dtypes and axis=1
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df = DataFrame({"A": range(3), "B": 2 * np.arange(3, dtype=np.float64)})
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expected = DataFrame({"A": [np.nan, np.nan, np.nan], "B": df["B"] / 2})
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result = df.diff(axis=1)
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tm.assert_frame_equal(result, expected)
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# GH#21437 mixed-float-dtypes
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df = DataFrame(
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{"a": np.arange(3, dtype="float32"), "b": np.arange(3, dtype="float64")}
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)
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result = df.diff(axis=1)
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expected = DataFrame({"a": df["a"] * np.nan, "b": df["b"] * 0})
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tm.assert_frame_equal(result, expected)
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def test_diff_axis1_mixed_dtypes_large_periods(self):
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# GH#32995 operate column-wise when we have mixed dtypes and axis=1
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df = DataFrame({"A": range(3), "B": 2 * np.arange(3, dtype=np.float64)})
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expected = df * np.nan
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result = df.diff(axis=1, periods=3)
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tm.assert_frame_equal(result, expected)
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def test_diff_axis1_mixed_dtypes_negative_periods(self):
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# GH#32995 operate column-wise when we have mixed dtypes and axis=1
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df = DataFrame({"A": range(3), "B": 2 * np.arange(3, dtype=np.float64)})
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expected = DataFrame({"A": -1.0 * df["A"], "B": df["B"] * np.nan})
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result = df.diff(axis=1, periods=-1)
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tm.assert_frame_equal(result, expected)
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def test_diff_sparse(self):
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# GH#28813 .diff() should work for sparse dataframes as well
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sparse_df = DataFrame([[0, 1], [1, 0]], dtype="Sparse[int]")
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result = sparse_df.diff()
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expected = DataFrame(
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[[np.nan, np.nan], [1.0, -1.0]], dtype=pd.SparseDtype("float", 0.0)
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)
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tm.assert_frame_equal(result, expected)
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@pytest.mark.parametrize(
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"axis,expected",
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[
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(
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0,
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DataFrame(
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{
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"a": [np.nan, 0, 1, 0, np.nan, np.nan, np.nan, 0],
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"b": [np.nan, 1, np.nan, np.nan, -2, 1, np.nan, np.nan],
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"c": np.repeat(np.nan, 8),
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"d": [np.nan, 3, 5, 7, 9, 11, 13, 15],
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},
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dtype="Int64",
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),
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),
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(
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1,
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DataFrame(
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{
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"a": np.repeat(np.nan, 8),
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"b": [0, 1, np.nan, 1, np.nan, np.nan, np.nan, 0],
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"c": np.repeat(np.nan, 8),
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"d": np.repeat(np.nan, 8),
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},
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dtype="Int64",
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),
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),
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],
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)
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def test_diff_integer_na(self, axis, expected):
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# GH#24171 IntegerNA Support for DataFrame.diff()
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df = DataFrame(
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{
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"a": np.repeat([0, 1, np.nan, 2], 2),
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"b": np.tile([0, 1, np.nan, 2], 2),
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"c": np.repeat(np.nan, 8),
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"d": np.arange(1, 9) ** 2,
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},
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dtype="Int64",
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)
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# Test case for default behaviour of diff
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result = df.diff(axis=axis)
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tm.assert_frame_equal(result, expected)
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def test_diff_readonly(self):
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# https://github.com/pandas-dev/pandas/issues/35559
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arr = np.random.randn(5, 2)
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arr.flags.writeable = False
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df = DataFrame(arr)
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result = df.diff()
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expected = DataFrame(np.array(df)).diff()
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tm.assert_frame_equal(result, expected)
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def test_diff_all_int_dtype(self, any_int_numpy_dtype):
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# GH 14773
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df = DataFrame(range(5))
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df = df.astype(any_int_numpy_dtype)
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result = df.diff()
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expected_dtype = (
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"float32" if any_int_numpy_dtype in ("int8", "int16") else "float64"
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)
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expected = DataFrame([np.nan, 1.0, 1.0, 1.0, 1.0], dtype=expected_dtype)
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tm.assert_frame_equal(result, expected)
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