test_hist_method.py

""" Test cases for .hist method """

import numpy as np
from numpy.random import randn
import pytest

import pandas.util._test_decorators as td

from pandas import DataFrame, Index, Series
import pandas._testing as tm
from pandas.tests.plotting.common import TestPlotBase, _check_plot_works


@td.skip_if_no_mpl
class TestSeriesPlots(TestPlotBase):
    def setup_method(self, method):
        TestPlotBase.setup_method(self, method)
        import matplotlib as mpl

        mpl.rcdefaults()

        self.ts = tm.makeTimeSeries()
        self.ts.name = "ts"

    @pytest.mark.slow
    def test_hist_legacy(self):
        _check_plot_works(self.ts.hist)
        _check_plot_works(self.ts.hist, grid=False)
        _check_plot_works(self.ts.hist, figsize=(8, 10))
        # _check_plot_works adds an ax so catch warning. see GH #13188
        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(self.ts.hist, by=self.ts.index.month)
        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(self.ts.hist, by=self.ts.index.month, bins=5)

        fig, ax = self.plt.subplots(1, 1)
        _check_plot_works(self.ts.hist, ax=ax)
        _check_plot_works(self.ts.hist, ax=ax, figure=fig)
        _check_plot_works(self.ts.hist, figure=fig)
        tm.close()

        fig, (ax1, ax2) = self.plt.subplots(1, 2)
        _check_plot_works(self.ts.hist, figure=fig, ax=ax1)
        _check_plot_works(self.ts.hist, figure=fig, ax=ax2)

        with pytest.raises(ValueError):
            self.ts.hist(by=self.ts.index, figure=fig)

    @pytest.mark.slow
    def test_hist_bins_legacy(self):
        df = DataFrame(np.random.randn(10, 2))
        ax = df.hist(bins=2)[0][0]
        assert len(ax.patches) == 2

    @pytest.mark.slow
    def test_hist_layout(self):
        df = self.hist_df
        with pytest.raises(ValueError):
            df.height.hist(layout=(1, 1))

        with pytest.raises(ValueError):
            df.height.hist(layout=[1, 1])

    @pytest.mark.slow
    def test_hist_layout_with_by(self):
        df = self.hist_df

        # _check_plot_works adds an `ax` kwarg to the method call
        # so we get a warning about an axis being cleared, even
        # though we don't explicing pass one, see GH #13188
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.gender, layout=(2, 1))
        self._check_axes_shape(axes, axes_num=2, layout=(2, 1))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.gender, layout=(3, -1))
        self._check_axes_shape(axes, axes_num=2, layout=(3, 1))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.category, layout=(4, 1))
        self._check_axes_shape(axes, axes_num=4, layout=(4, 1))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.category, layout=(2, -1))
        self._check_axes_shape(axes, axes_num=4, layout=(2, 2))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.category, layout=(3, -1))
        self._check_axes_shape(axes, axes_num=4, layout=(3, 2))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.category, layout=(-1, 4))
        self._check_axes_shape(axes, axes_num=4, layout=(1, 4))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.height.hist, by=df.classroom, layout=(2, 2))
        self._check_axes_shape(axes, axes_num=3, layout=(2, 2))

        axes = df.height.hist(by=df.category, layout=(4, 2), figsize=(12, 7))
        self._check_axes_shape(axes, axes_num=4, layout=(4, 2), figsize=(12, 7))

    @pytest.mark.slow
    def test_hist_no_overlap(self):
        from matplotlib.pyplot import subplot, gcf

        x = Series(randn(2))
        y = Series(randn(2))
        subplot(121)
        x.hist()
        subplot(122)
        y.hist()
        fig = gcf()
        axes = fig.axes
        assert len(axes) == 2

    @pytest.mark.slow
    def test_hist_by_no_extra_plots(self):
        df = self.hist_df
        axes = df.height.hist(by=df.gender)  # noqa
        assert len(self.plt.get_fignums()) == 1

    @pytest.mark.slow
    def test_plot_fails_when_ax_differs_from_figure(self):
        from pylab import figure

        fig1 = figure()
        fig2 = figure()
        ax1 = fig1.add_subplot(111)
        with pytest.raises(AssertionError):
            self.ts.hist(ax=ax1, figure=fig2)


@td.skip_if_no_mpl
class TestDataFramePlots(TestPlotBase):
    @pytest.mark.slow
    def test_hist_df_legacy(self):
        from matplotlib.patches import Rectangle

        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(self.hist_df.hist)

        # make sure layout is handled
        df = DataFrame(randn(100, 3))
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.hist, grid=False)
        self._check_axes_shape(axes, axes_num=3, layout=(2, 2))
        assert not axes[1, 1].get_visible()

        df = DataFrame(randn(100, 1))
        _check_plot_works(df.hist)

        # make sure layout is handled
        df = DataFrame(randn(100, 6))
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.hist, layout=(4, 2))
        self._check_axes_shape(axes, axes_num=6, layout=(4, 2))

        # make sure sharex, sharey is handled
        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(df.hist, sharex=True, sharey=True)

        # handle figsize arg
        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(df.hist, figsize=(8, 10))

        # check bins argument
        with tm.assert_produces_warning(UserWarning):
            _check_plot_works(df.hist, bins=5)

        # make sure xlabelsize and xrot are handled
        ser = df[0]
        xf, yf = 20, 18
        xrot, yrot = 30, 40
        axes = ser.hist(xlabelsize=xf, xrot=xrot, ylabelsize=yf, yrot=yrot)
        self._check_ticks_props(
            axes, xlabelsize=xf, xrot=xrot, ylabelsize=yf, yrot=yrot
        )

        xf, yf = 20, 18
        xrot, yrot = 30, 40
        axes = df.hist(xlabelsize=xf, xrot=xrot, ylabelsize=yf, yrot=yrot)
        self._check_ticks_props(
            axes, xlabelsize=xf, xrot=xrot, ylabelsize=yf, yrot=yrot
        )

        tm.close()

        ax = ser.hist(cumulative=True, bins=4, density=True)
        # height of last bin (index 5) must be 1.0
        rects = [x for x in ax.get_children() if isinstance(x, Rectangle)]
        tm.assert_almost_equal(rects[-1].get_height(), 1.0)

        tm.close()
        ax = ser.hist(log=True)
        # scale of y must be 'log'
        self._check_ax_scales(ax, yaxis="log")

        tm.close()

        # propagate attr exception from matplotlib.Axes.hist
        with pytest.raises(AttributeError):
            ser.hist(foo="bar")

    @pytest.mark.slow
    def test_hist_non_numerical_raises(self):
        # gh-10444
        df = DataFrame(np.random.rand(10, 2))
        df_o = df.astype(np.object)

        msg = "hist method requires numerical columns, nothing to plot."
        with pytest.raises(ValueError, match=msg):
            df_o.hist()

    @pytest.mark.slow
    def test_hist_layout(self):
        df = DataFrame(randn(100, 3))

        layout_to_expected_size = (
            {"layout": None, "expected_size": (2, 2)},  # default is 2x2
            {"layout": (2, 2), "expected_size": (2, 2)},
            {"layout": (4, 1), "expected_size": (4, 1)},
            {"layout": (1, 4), "expected_size": (1, 4)},
            {"layout": (3, 3), "expected_size": (3, 3)},
            {"layout": (-1, 4), "expected_size": (1, 4)},
            {"layout": (4, -1), "expected_size": (4, 1)},
            {"layout": (-1, 2), "expected_size": (2, 2)},
            {"layout": (2, -1), "expected_size": (2, 2)},
        )

        for layout_test in layout_to_expected_size:
            axes = df.hist(layout=layout_test["layout"])
            expected = layout_test["expected_size"]
            self._check_axes_shape(axes, axes_num=3, layout=expected)

        # layout too small for all 4 plots
        with pytest.raises(ValueError):
            df.hist(layout=(1, 1))

        # invalid format for layout
        with pytest.raises(ValueError):
            df.hist(layout=(1,))
        with pytest.raises(ValueError):
            df.hist(layout=(-1, -1))

    @pytest.mark.slow
    # GH 9351
    def test_tight_layout(self):
        df = DataFrame(randn(100, 3))
        _check_plot_works(df.hist)
        self.plt.tight_layout()

        tm.close()

    def test_hist_subplot_xrot(self):
        # GH 30288
        df = DataFrame(
            {
                "length": [1.5, 0.5, 1.2, 0.9, 3],
                "animal": ["pig", "rabbit", "pig", "pig", "rabbit"],
            }
        )
        axes = _check_plot_works(
            df.hist,
            filterwarnings="always",
            column="length",
            by="animal",
            bins=5,
            xrot=0,
        )
        self._check_ticks_props(axes, xrot=0)

    @pytest.mark.parametrize(
        "column, expected",
        [
            (None, ["width", "length", "height"]),
            (["length", "width", "height"], ["length", "width", "height"]),
        ],
    )
    def test_hist_column_order_unchanged(self, column, expected):
        # GH29235

        df = DataFrame(
            {
                "width": [0.7, 0.2, 0.15, 0.2, 1.1],
                "length": [1.5, 0.5, 1.2, 0.9, 3],
                "height": [3, 0.5, 3.4, 2, 1],
            },
            index=["pig", "rabbit", "duck", "chicken", "horse"],
        )

        axes = _check_plot_works(df.hist, column=column, layout=(1, 3))
        result = [axes[0, i].get_title() for i in range(3)]

        assert result == expected

    @pytest.mark.slow
    @pytest.mark.parametrize("by", [None, "b"])
    @pytest.mark.parametrize("label", [None, "c"])
    def test_hist_with_legend(self, by, label):
        expected_labels = label or "a"
        expected_axes_num = 1 if by is None else 2
        expected_layout = (1, 1) if by is None else (1, 2)

        index = 15 * [1] + 15 * [2]
        s = Series(np.random.randn(30), index=index, name="a")
        s.index.name = "b"

        kwargs = {"legend": True, "by": by}
        if label is not None:
            # Behavior differs if kwargs contains "label": None
            kwargs["label"] = label

        _check_plot_works(s.hist, **kwargs)
        axes = s.hist(**kwargs)
        self._check_axes_shape(axes, axes_num=expected_axes_num, layout=expected_layout)
        self._check_legend_labels(axes, expected_labels)


@td.skip_if_no_mpl
class TestDataFrameGroupByPlots(TestPlotBase):
    @pytest.mark.slow
    def test_grouped_hist_legacy(self):
        from matplotlib.patches import Rectangle
        from pandas.plotting._matplotlib.hist import _grouped_hist

        df = DataFrame(randn(500, 2), columns=["A", "B"])
        df["C"] = np.random.randint(0, 4, 500)
        df["D"] = ["X"] * 500

        axes = _grouped_hist(df.A, by=df.C)
        self._check_axes_shape(axes, axes_num=4, layout=(2, 2))

        tm.close()
        axes = df.hist(by=df.C)
        self._check_axes_shape(axes, axes_num=4, layout=(2, 2))

        tm.close()
        # group by a key with single value
        axes = df.hist(by="D", rot=30)
        self._check_axes_shape(axes, axes_num=1, layout=(1, 1))
        self._check_ticks_props(axes, xrot=30)

        tm.close()
        # make sure kwargs to hist are handled
        xf, yf = 20, 18
        xrot, yrot = 30, 40

        axes = _grouped_hist(
            df.A,
            by=df.C,
            cumulative=True,
            bins=4,
            xlabelsize=xf,
            xrot=xrot,
            ylabelsize=yf,
            yrot=yrot,
            density=True,
        )
        # height of last bin (index 5) must be 1.0
        for ax in axes.ravel():
            rects = [x for x in ax.get_children() if isinstance(x, Rectangle)]
            height = rects[-1].get_height()
            tm.assert_almost_equal(height, 1.0)
        self._check_ticks_props(
            axes, xlabelsize=xf, xrot=xrot, ylabelsize=yf, yrot=yrot
        )

        tm.close()
        axes = _grouped_hist(df.A, by=df.C, log=True)
        # scale of y must be 'log'
        self._check_ax_scales(axes, yaxis="log")

        tm.close()
        # propagate attr exception from matplotlib.Axes.hist
        with pytest.raises(AttributeError):
            _grouped_hist(df.A, by=df.C, foo="bar")

        msg = "Specify figure size by tuple instead"
        with pytest.raises(ValueError, match=msg):
            df.hist(by="C", figsize="default")

    @pytest.mark.slow
    def test_grouped_hist_legacy2(self):
        n = 10
        weight = Series(np.random.normal(166, 20, size=n))
        height = Series(np.random.normal(60, 10, size=n))
        with tm.RNGContext(42):
            gender_int = np.random.choice([0, 1], size=n)
        df_int = DataFrame({"height": height, "weight": weight, "gender": gender_int})
        gb = df_int.groupby("gender")
        axes = gb.hist()
        assert len(axes) == 2
        assert len(self.plt.get_fignums()) == 2
        tm.close()

    @pytest.mark.slow
    def test_grouped_hist_layout(self):
        df = self.hist_df
        msg = "Layout of 1x1 must be larger than required size 2"
        with pytest.raises(ValueError, match=msg):
            df.hist(column="weight", by=df.gender, layout=(1, 1))

        msg = "Layout of 1x3 must be larger than required size 4"
        with pytest.raises(ValueError, match=msg):
            df.hist(column="height", by=df.category, layout=(1, 3))

        msg = "At least one dimension of layout must be positive"
        with pytest.raises(ValueError, match=msg):
            df.hist(column="height", by=df.category, layout=(-1, -1))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(
                df.hist, column="height", by=df.gender, layout=(2, 1)
            )
        self._check_axes_shape(axes, axes_num=2, layout=(2, 1))

        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(
                df.hist, column="height", by=df.gender, layout=(2, -1)
            )
        self._check_axes_shape(axes, axes_num=2, layout=(2, 1))

        axes = df.hist(column="height", by=df.category, layout=(4, 1))
        self._check_axes_shape(axes, axes_num=4, layout=(4, 1))

        axes = df.hist(column="height", by=df.category, layout=(-1, 1))
        self._check_axes_shape(axes, axes_num=4, layout=(4, 1))

        axes = df.hist(column="height", by=df.category, layout=(4, 2), figsize=(12, 8))
        self._check_axes_shape(axes, axes_num=4, layout=(4, 2), figsize=(12, 8))
        tm.close()

        # GH 6769
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(
                df.hist, column="height", by="classroom", layout=(2, 2)
            )
        self._check_axes_shape(axes, axes_num=3, layout=(2, 2))

        # without column
        with tm.assert_produces_warning(UserWarning):
            axes = _check_plot_works(df.hist, by="classroom")
        self._check_axes_shape(axes, axes_num=3, layout=(2, 2))

        axes = df.hist(by="gender", layout=(3, 5))
        self._check_axes_shape(axes, axes_num=2, layout=(3, 5))

        axes = df.hist(column=["height", "weight", "category"])
        self._check_axes_shape(axes, axes_num=3, layout=(2, 2))

    @pytest.mark.slow
    def test_grouped_hist_multiple_axes(self):
        # GH 6970, GH 7069
        df = self.hist_df

        fig, axes = self.plt.subplots(2, 3)
        returned = df.hist(column=["height", "weight", "category"], ax=axes[0])
        self._check_axes_shape(returned, axes_num=3, layout=(1, 3))
        tm.assert_numpy_array_equal(returned, axes[0])
        assert returned[0].figure is fig
        returned = df.hist(by="classroom", ax=axes[1])
        self._check_axes_shape(returned, axes_num=3, layout=(1, 3))
        tm.assert_numpy_array_equal(returned, axes[1])
        assert returned[0].figure is fig

        with pytest.raises(ValueError):
            fig, axes = self.plt.subplots(2, 3)
            # pass different number of axes from required
            axes = df.hist(column="height", ax=axes)

    @pytest.mark.slow
    def test_axis_share_x(self):
        df = self.hist_df
        # GH4089
        ax1, ax2 = df.hist(column="height", by=df.gender, sharex=True)

        # share x
        assert ax1._shared_x_axes.joined(ax1, ax2)
        assert ax2._shared_x_axes.joined(ax1, ax2)

        # don't share y
        assert not ax1._shared_y_axes.joined(ax1, ax2)
        assert not ax2._shared_y_axes.joined(ax1, ax2)

    @pytest.mark.slow
    def test_axis_share_y(self):
        df = self.hist_df
        ax1, ax2 = df.hist(column="height", by=df.gender, sharey=True)

        # share y
        assert ax1._shared_y_axes.joined(ax1, ax2)
        assert ax2._shared_y_axes.joined(ax1, ax2)

        # don't share x
        assert not ax1._shared_x_axes.joined(ax1, ax2)
        assert not ax2._shared_x_axes.joined(ax1, ax2)

    @pytest.mark.slow
    def test_axis_share_xy(self):
        df = self.hist_df
        ax1, ax2 = df.hist(column="height", by=df.gender, sharex=True, sharey=True)

        # share both x and y
        assert ax1._shared_x_axes.joined(ax1, ax2)
        assert ax2._shared_x_axes.joined(ax1, ax2)

        assert ax1._shared_y_axes.joined(ax1, ax2)
        assert ax2._shared_y_axes.joined(ax1, ax2)

    @pytest.mark.slow
    @pytest.mark.parametrize("by", [None, "c"])
    @pytest.mark.parametrize("column", [None, "b"])
    @pytest.mark.parametrize("label", [None, "d"])
    def test_hist_with_legend(self, by, column, label):
        expected_axes_num = 1 if by is None and column is not None else 2
        expected_layout = (1, expected_axes_num)
        expected_labels = label or column or ["a", "b"]
        if by is not None:
            expected_labels = [expected_labels] * 2

        index = Index(15 * [1] + 15 * [2], name="c")
        df = DataFrame(np.random.randn(30, 2), index=index, columns=["a", "b"])

        kwargs = {"legend": True, "by": by, "column": column}
        if label is not None:
            # Behavior differs if kwargs contains "label": None
            kwargs["label"] = label

        _check_plot_works(df.hist, **kwargs)
        axes = df.hist(**kwargs)
        self._check_axes_shape(axes, axes_num=expected_axes_num, layout=expected_layout)
        if by is None:
            axes = axes[0]
        for expected_label, ax in zip(expected_labels, axes):
            self._check_legend_labels(ax, expected_label)