SpringFocus/venv/lib/python3.8/site-packages/pandas/tests/frame/test_mutate_columns.py

import re

import numpy as np
import pytest

from pandas import DataFrame, Index, MultiIndex, Series
import pandas._testing as tm

# Column add, remove, delete.


class TestDataFrameMutateColumns:
    def test_assign(self):
        df = DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
        original = df.copy()
        result = df.assign(C=df.B / df.A)
        expected = df.copy()
        expected["C"] = [4, 2.5, 2]
        tm.assert_frame_equal(result, expected)

        # lambda syntax
        result = df.assign(C=lambda x: x.B / x.A)
        tm.assert_frame_equal(result, expected)

        # original is unmodified
        tm.assert_frame_equal(df, original)

        # Non-Series array-like
        result = df.assign(C=[4, 2.5, 2])
        tm.assert_frame_equal(result, expected)
        # original is unmodified
        tm.assert_frame_equal(df, original)

        result = df.assign(B=df.B / df.A)
        expected = expected.drop("B", axis=1).rename(columns={"C": "B"})
        tm.assert_frame_equal(result, expected)

        # overwrite
        result = df.assign(A=df.A + df.B)
        expected = df.copy()
        expected["A"] = [5, 7, 9]
        tm.assert_frame_equal(result, expected)

        # lambda
        result = df.assign(A=lambda x: x.A + x.B)
        tm.assert_frame_equal(result, expected)

    def test_assign_multiple(self):
        df = DataFrame([[1, 4], [2, 5], [3, 6]], columns=["A", "B"])
        result = df.assign(C=[7, 8, 9], D=df.A, E=lambda x: x.B)
        expected = DataFrame(
            [[1, 4, 7, 1, 4], [2, 5, 8, 2, 5], [3, 6, 9, 3, 6]], columns=list("ABCDE")
        )
        tm.assert_frame_equal(result, expected)

    def test_assign_order(self):
        # GH 9818
        df = DataFrame([[1, 2], [3, 4]], columns=["A", "B"])
        result = df.assign(D=df.A + df.B, C=df.A - df.B)

        expected = DataFrame([[1, 2, 3, -1], [3, 4, 7, -1]], columns=list("ABDC"))
        tm.assert_frame_equal(result, expected)
        result = df.assign(C=df.A - df.B, D=df.A + df.B)

        expected = DataFrame([[1, 2, -1, 3], [3, 4, -1, 7]], columns=list("ABCD"))

        tm.assert_frame_equal(result, expected)

    def test_assign_bad(self):
        df = DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})

        # non-keyword argument
        with pytest.raises(TypeError):
            df.assign(lambda x: x.A)
        with pytest.raises(AttributeError):
            df.assign(C=df.A, D=df.A + df.C)

    def test_assign_dependent(self):
        df = DataFrame({"A": [1, 2], "B": [3, 4]})

        result = df.assign(C=df.A, D=lambda x: x["A"] + x["C"])
        expected = DataFrame([[1, 3, 1, 2], [2, 4, 2, 4]], columns=list("ABCD"))
        tm.assert_frame_equal(result, expected)

        result = df.assign(C=lambda df: df.A, D=lambda df: df["A"] + df["C"])
        expected = DataFrame([[1, 3, 1, 2], [2, 4, 2, 4]], columns=list("ABCD"))
        tm.assert_frame_equal(result, expected)

    def test_insert_error_msmgs(self):

        # GH 7432
        df = DataFrame(
            {"foo": ["a", "b", "c"], "bar": [1, 2, 3], "baz": ["d", "e", "f"]}
        ).set_index("foo")
        s = DataFrame(
            {"foo": ["a", "b", "c", "a"], "fiz": ["g", "h", "i", "j"]}
        ).set_index("foo")
        msg = "cannot reindex from a duplicate axis"
        with pytest.raises(ValueError, match=msg):
            df["newcol"] = s

        # GH 4107, more descriptive error message
        df = DataFrame(np.random.randint(0, 2, (4, 4)), columns=["a", "b", "c", "d"])

        msg = "incompatible index of inserted column with frame index"
        with pytest.raises(TypeError, match=msg):
            df["gr"] = df.groupby(["b", "c"]).count()

    def test_insert_benchmark(self):
        # from the vb_suite/frame_methods/frame_insert_columns
        N = 10
        K = 5
        df = DataFrame(index=range(N))
        new_col = np.random.randn(N)
        for i in range(K):
            df[i] = new_col
        expected = DataFrame(np.repeat(new_col, K).reshape(N, K), index=range(N))
        tm.assert_frame_equal(df, expected)

    def test_insert(self):
        df = DataFrame(
            np.random.randn(5, 3), index=np.arange(5), columns=["c", "b", "a"]
        )

        df.insert(0, "foo", df["a"])
        tm.assert_index_equal(df.columns, Index(["foo", "c", "b", "a"]))
        tm.assert_series_equal(df["a"], df["foo"], check_names=False)

        df.insert(2, "bar", df["c"])
        tm.assert_index_equal(df.columns, Index(["foo", "c", "bar", "b", "a"]))
        tm.assert_almost_equal(df["c"], df["bar"], check_names=False)

        # diff dtype

        # new item
        df["x"] = df["a"].astype("float32")
        result = df.dtypes
        expected = Series(
            [np.dtype("float64")] * 5 + [np.dtype("float32")],
            index=["foo", "c", "bar", "b", "a", "x"],
        )
        tm.assert_series_equal(result, expected)

        # replacing current (in different block)
        df["a"] = df["a"].astype("float32")
        result = df.dtypes
        expected = Series(
            [np.dtype("float64")] * 4 + [np.dtype("float32")] * 2,
            index=["foo", "c", "bar", "b", "a", "x"],
        )
        tm.assert_series_equal(result, expected)

        df["y"] = df["a"].astype("int32")
        result = df.dtypes
        expected = Series(
            [np.dtype("float64")] * 4 + [np.dtype("float32")] * 2 + [np.dtype("int32")],
            index=["foo", "c", "bar", "b", "a", "x", "y"],
        )
        tm.assert_series_equal(result, expected)

        with pytest.raises(ValueError, match="already exists"):
            df.insert(1, "a", df["b"])
        msg = "cannot insert c, already exists"
        with pytest.raises(ValueError, match=msg):
            df.insert(1, "c", df["b"])

        df.columns.name = "some_name"
        # preserve columns name field
        df.insert(0, "baz", df["c"])
        assert df.columns.name == "some_name"

        # GH 13522
        df = DataFrame(index=["A", "B", "C"])
        df["X"] = df.index
        df["X"] = ["x", "y", "z"]
        exp = DataFrame(data={"X": ["x", "y", "z"]}, index=["A", "B", "C"])
        tm.assert_frame_equal(df, exp)

    def test_delitem(self, float_frame):
        del float_frame["A"]
        assert "A" not in float_frame

    def test_delitem_multiindex(self):
        midx = MultiIndex.from_product([["A", "B"], [1, 2]])
        df = DataFrame(np.random.randn(4, 4), columns=midx)
        assert len(df.columns) == 4
        assert ("A",) in df.columns
        assert "A" in df.columns

        result = df["A"]
        assert isinstance(result, DataFrame)
        del df["A"]

        assert len(df.columns) == 2

        # A still in the levels, BUT get a KeyError if trying
        # to delete
        assert ("A",) not in df.columns
        with pytest.raises(KeyError, match=re.escape("('A',)")):
            del df[("A",)]

        # behavior of dropped/deleted MultiIndex levels changed from
        # GH 2770 to GH 19027: MultiIndex no longer '.__contains__'
        # levels which are dropped/deleted
        assert "A" not in df.columns
        with pytest.raises(KeyError, match=re.escape("('A',)")):
            del df["A"]

    def test_pop(self, float_frame):
        float_frame.columns.name = "baz"

        float_frame.pop("A")
        assert "A" not in float_frame

        float_frame["foo"] = "bar"
        float_frame.pop("foo")
        assert "foo" not in float_frame
        assert float_frame.columns.name == "baz"

        # gh-10912: inplace ops cause caching issue
        a = DataFrame([[1, 2, 3], [4, 5, 6]], columns=["A", "B", "C"], index=["X", "Y"])
        b = a.pop("B")
        b += 1

        # original frame
        expected = DataFrame([[1, 3], [4, 6]], columns=["A", "C"], index=["X", "Y"])
        tm.assert_frame_equal(a, expected)

        # result
        expected = Series([2, 5], index=["X", "Y"], name="B") + 1
        tm.assert_series_equal(b, expected)

    def test_pop_non_unique_cols(self):
        df = DataFrame({0: [0, 1], 1: [0, 1], 2: [4, 5]})
        df.columns = ["a", "b", "a"]

        res = df.pop("a")
        assert type(res) == DataFrame
        assert len(res) == 2
        assert len(df.columns) == 1
        assert "b" in df.columns
        assert "a" not in df.columns
        assert len(df.index) == 2

    def test_insert_column_bug_4032(self):

        # GH4032, inserting a column and renaming causing errors
        df = DataFrame({"b": [1.1, 2.2]})
        df = df.rename(columns={})
        df.insert(0, "a", [1, 2])

        result = df.rename(columns={})
        str(result)
        expected = DataFrame([[1, 1.1], [2, 2.2]], columns=["a", "b"])
        tm.assert_frame_equal(result, expected)
        df.insert(0, "c", [1.3, 2.3])

        result = df.rename(columns={})
        str(result)

        expected = DataFrame([[1.3, 1, 1.1], [2.3, 2, 2.2]], columns=["c", "a", "b"])
        tm.assert_frame_equal(result, expected)