SkewT.fill_betweenx() - Code Metrics - Inspection of "Skew T Masked Data" - Unidata/MetPy - Measure and Improve Code Quality continuously with Scrutinizer

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Pull Request — master (#378)

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created 2017-03-31 15:45 UTC
SkewT.fill_betweenx() A

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# Copyright (c) 2008-2015 MetPy Developers.
# Distributed under the terms of the BSD 3-Clause License.
# SPDX-License-Identifier: BSD-3-Clause
"""Make Skew-T Log-P based plots.

Contain tools for making Skew-T Log-P plots, including the base plotting class,
`SkewT`, as well as a class for making a `Hodograph`.
"""

from matplotlib.axes import Axes
import matplotlib.axis as maxis
from matplotlib.collections import LineCollection
from matplotlib.patches import Circle
from matplotlib.projections import register_projection
import matplotlib.spines as mspines
from matplotlib.ticker import MultipleLocator, NullFormatter, ScalarFormatter
import matplotlib.transforms as transforms
import numpy as np

from ._util import colored_line, delete_masked_points
from ..calc import dewpoint, dry_lapse, moist_lapse, vapor_pressure
from ..package_tools import Exporter
from ..units import units

exporter = Exporter(globals())


class SkewXTick(maxis.XTick):
    r"""Make x-axis ticks for Skew-T plots.

    This class adds to the standard :class:`matplotlib.axis.XTick` dynamic checking
    for whether a top or bottom tick is actually within the data limits at that part
    and draw as appropriate. It also performs similar checking for gridlines.
    """

    def update_position(self, loc):
        """Set the location of tick in data coords with scalar *loc*."""
        # This ensures that the new value of the location is set before
        # any other updates take place.
        self._loc = loc
        super(SkewXTick, self).update_position(loc)

    def _has_default_loc(self):
        return self.get_loc() is None

    def _need_lower(self):
        return (self._has_default_loc() or
                transforms.interval_contains(self.axes.lower_xlim,
                                             self.get_loc()))

    def _need_upper(self):
        return (self._has_default_loc() or
                transforms.interval_contains(self.axes.upper_xlim,
                                             self.get_loc()))

    @property
    def gridOn(self):  # noqa: N802
        """Control whether the gridline is drawn for this tick."""
        return (self._gridOn and (self._has_default_loc() or
                transforms.interval_contains(self.get_view_interval(),
                                             self.get_loc())))

    @gridOn.setter
    def gridOn(self, value):  # noqa: N802
        self._gridOn = value

    @property
    def tick1On(self):  # noqa: N802
        """Control whether the lower tick mark is drawn for this tick."""
        return self._tick1On and self._need_lower()

    @tick1On.setter
    def tick1On(self, value):  # noqa: N802
        self._tick1On = value

    @property
    def label1On(self):  # noqa: N802
        """Control whether the lower tick label is drawn for this tick."""
        return self._label1On and self._need_lower()

    @label1On.setter
    def label1On(self, value):  # noqa: N802
        self._label1On = value

    @property
    def tick2On(self):  # noqa: N802
        """Control whether the upper tick mark is drawn for this tick."""
        return self._tick2On and self._need_upper()

    @tick2On.setter
    def tick2On(self, value):  # noqa: N802
        self._tick2On = value

    @property
    def label2On(self):  # noqa: N802
        """Control whether the upper tick label is drawn for this tick."""
        return self._label2On and self._need_upper()

    @label2On.setter
    def label2On(self, value):  # noqa: N802
        self._label2On = value

    def get_view_interval(self):
        """Get the view interval."""
        return self.axes.xaxis.get_view_interval()


class SkewXAxis(maxis.XAxis):
    r"""Make an x-axis that works properly for Skew-T plots.

    This class exists to force the use of our custom :class:`SkewXTick` as well
    as provide a custom value for interview that combines the extents of the
    upper and lower x-limits from the axes.
    """

    def _get_tick(self, major):
        return SkewXTick(self.axes, None, '', major=major)

    def get_view_interval(self):
        """Get the view interval."""
        return self.axes.upper_xlim[0], self.axes.lower_xlim[1]


class SkewSpine(mspines.Spine):
    r"""Make an x-axis spine that works properly for Skew-T plots.

    This class exists to use the separate x-limits from the axes to properly
    locate the spine.
    """

    def _adjust_location(self):
        pts = self._path.vertices
        if self.spine_type == 'top':
            pts[:, 0] = self.axes.upper_xlim
        else:
            pts[:, 0] = self.axes.lower_xlim


class SkewXAxes(Axes):
    r"""Make a set of axes for Skew-T plots.

    This class handles registration of the skew-xaxes as a projection as well as setting up
    the appropriate transformations. It also makes sure we use our instances for spines
    and x-axis: :class:`SkewSpine` and :class:`SkewXAxis`. It provides properties to
    facilitate finding the x-limits for the bottom and top of the plot as well.
    """

    # The projection must specify a name.  This will be used be the
    # user to select the projection, i.e. ``subplot(111,
    # projection='skewx')``.
    name = 'skewx'

    def __init__(self, *args, **kwargs):
        r"""Initialize `SkewXAxes`.

        Parameters
        ----------
        args : Arbitrary positional arguments
            Passed to :class:`matplotlib.axes.Axes`

        position: int, optional
            The rotation of the x-axis against the y-axis, in degrees.

        kwargs : Arbitrary keyword arguments
            Passed to :class:`matplotlib.axes.Axes`
        """
        # This needs to be popped and set before moving on
        self.rot = kwargs.pop('rotation', 30)
        Axes.__init__(self, *args, **kwargs)

    def _init_axis(self):
        # Taken from Axes and modified to use our modified X-axis
        self.xaxis = SkewXAxis(self)
        self.spines['top'].register_axis(self.xaxis)
        self.spines['bottom'].register_axis(self.xaxis)
        self.yaxis = maxis.YAxis(self)
        self.spines['left'].register_axis(self.yaxis)
        self.spines['right'].register_axis(self.yaxis)

    def _gen_axes_spines(self, locations=None, offset=0.0, units='inches'):
        # pylint: disable=unused-argument
        spines = {'top': SkewSpine.linear_spine(self, 'top'),
                  'bottom': mspines.Spine.linear_spine(self, 'bottom'),
                  'left': mspines.Spine.linear_spine(self, 'left'),
                  'right': mspines.Spine.linear_spine(self, 'right')}
        return spines

    def _set_lim_and_transforms(self):
        """Set limits and transforms.

        This is called once when the plot is created to set up all the
        transforms for the data, text and grids.
        """
        # Get the standard transform setup from the Axes base class
        Axes._set_lim_and_transforms(self)

        # Need to put the skew in the middle, after the scale and limits,
        # but before the transAxes. This way, the skew is done in Axes
        # coordinates thus performing the transform around the proper origin
        # We keep the pre-transAxes transform around for other users, like the
        # spines for finding bounds
        self.transDataToAxes = (self.transScale +
                                (self.transLimits +
                                 transforms.Affine2D().skew_deg(self.rot, 0)))

        # Create the full transform from Data to Pixels
        self.transData = self.transDataToAxes + self.transAxes

        # Blended transforms like this need to have the skewing applied using
        # both axes, in axes coords like before.
        self._xaxis_transform = (transforms.blended_transform_factory(
            self.transScale + self.transLimits,
            transforms.IdentityTransform()) +
            transforms.Affine2D().skew_deg(self.rot, 0)) + self.transAxes

    @property
    def lower_xlim(self):
        """Get the data limits for the x-axis along the bottom of the axes."""
        return self.axes.viewLim.intervalx

    @property
    def upper_xlim(self):
        """Get the data limits for the x-axis along the top of the axes."""
        return self.transDataToAxes.inverted().transform([[0., 1.], [1., 1.]])[:, 0]


# Now register the projection with matplotlib so the user can select
# it.
register_projection(SkewXAxes)


@exporter.export
class SkewT(object):
    r"""Make Skew-T log-P plots of data.

    This class simplifies the process of creating Skew-T log-P plots in
    using matplotlib. It handles requesting the appropriate skewed projection,
    and provides simplified wrappers to make it easy to plot data, add wind
    barbs, and add other lines to the plots (e.g. dry adiabats)

    Attributes
    ----------
    ax : `matplotlib.axes.Axes`
        The underlying Axes instance, which can be used for calling additional
        plot functions (e.g. `axvline`)
    """

    def __init__(self, fig=None, rotation=30, subplot=(1, 1, 1)):
        r"""Create SkewT - logP plots.

        Parameters
        ----------
        fig : matplotlib.figure.Figure, optional
            Source figure to use for plotting. If none is given, a new
            :class:`matplotlib.figure.Figure` instance will be created.
        rotation : float or int, optional
            Controls the rotation of temperature relative to horizontal. Given
            in degrees counterclockwise from x-axis. Defaults to 30 degrees.
        subplot : tuple[int, int, int] or `matplotlib.gridspec.SubplotSpec` instance, optional
            Controls the size/position of the created subplot. This allows creating
            the skewT as part of a collection of subplots. If subplot is a tuple, it
            should conform to the specification used for
            :meth:`matplotlib.figure.Figure.add_subplot`. The
            :class:`matplotlib.gridspec.SubplotSpec`
            can be created by using :class:`matplotlib.gridspec.GridSpec`.
        """
        if fig is None:
            import matplotlib.pyplot as plt
            figsize = plt.rcParams.get('figure.figsize', (7, 7))
            fig = plt.figure(figsize=figsize)
        self._fig = fig

        # Handle being passed a tuple for the subplot, or a GridSpec instance
        try:
            len(subplot)
        except TypeError:
            subplot = (subplot,)
        self.ax = fig.add_subplot(*subplot, projection='skewx', rotation=rotation)
        self.ax.grid(True)

    def fill_betweenx(self, y, x1, x2=0, **kwargs):
        y, x1, x2, kwargs['where'] = delete_masked_points(y, x1, x2, kwargs['where'])
        self.ax.fill_betweenx(y, x1, x2, **kwargs)

    def plot(self, p, t, *args, **kwargs):
        r"""Plot data.

        Simple wrapper around plot so that pressure is the first (independent)
        input. This is essentially a wrapper around `semilogy`. It also
        sets some appropriate ticking and plot ranges.

        Parameters
        ----------
        p : array_like
            pressure values
        t : array_like
            temperature values, can also be used for things like dew point
        args
            Other positional arguments to pass to :func:`~matplotlib.pyplot.semilogy`

        kwargs
            Other keyword arguments to pass to :func:`~matplotlib.pyplot.semilogy`

        Returns
        -------
        list[matplotlib.lines.Line2D]
            lines plotted

        See Also
        --------
        :func:`matplotlib.pyplot.semilogy`
        """
        # Skew-T logP plotting
        t, p = delete_masked_points(t, p)
        l = self.ax.semilogy(t, p, *args, **kwargs)

        # Disables the log-formatting that comes with semilogy
        self.ax.yaxis.set_major_formatter(ScalarFormatter())
        self.ax.yaxis.set_major_locator(MultipleLocator(100))
        self.ax.yaxis.set_minor_formatter(NullFormatter())
        if not self.ax.yaxis_inverted():
            self.ax.invert_yaxis()

        # Try to make sane default temperature plotting
        self.ax.xaxis.set_major_locator(MultipleLocator(10))
        self.ax.set_xlim(-50, 50)

        return l

    def plot_barbs(self, p, u, v, xloc=1.0, x_clip_radius=0.08, y_clip_radius=0.08, **kwargs):
        r"""Plot wind barbs.

        Adds wind barbs to the skew-T plot. This is a wrapper around the
        `barbs` command that adds to appropriate transform to place the
        barbs in a vertical line, located as a function of pressure.

        Parameters
        ----------
        p : array_like
            pressure values
        u : array_like
            U (East-West) component of wind
        v : array_like
            V (North-South) component of wind
        xloc : float, optional
            Position for the barbs, in normalized axes coordinates, where 0.0
            denotes far left and 1.0 denotes far right. Defaults to far right.
        x_clip_radius : float, optional
            Space, in normalized axes coordinates, to leave before clipping
            wind barbs in the x-direction. Defaults to 0.08.
        y_clip_radius : float, optional

            Space, in normalized axes coordinates, to leave above/below plot
            before clipping wind barbs in the y-direction. Defaults to 0.08.
        kwargs
            Other keyword arguments to pass to :func:`~matplotlib.pyplot.barbs`

        Returns
        -------
        matplotlib.quiver.Barbs
            instance created

        See Also
        --------
        :func:`matplotlib.pyplot.barbs`
        """
        # Assemble array of x-locations in axes space
        x = np.empty_like(p)
        x.fill(xloc)

        # Do barbs plot at this location
        b = self.ax.barbs(x, p, u, v,
                          transform=self.ax.get_yaxis_transform(which='tick2'),
                          clip_on=True, **kwargs)

        # Override the default clip box, which is the axes rectangle, so we can have
        # barbs that extend outside.
        ax_bbox = transforms.Bbox([[xloc - x_clip_radius, -y_clip_radius],
                                   [xloc + x_clip_radius, 1.0 + y_clip_radius]])
        b.set_clip_box(transforms.TransformedBbox(ax_bbox, self.ax.transAxes))
        return b

    def plot_dry_adiabats(self, t0=None, p=None, **kwargs):
        r"""Plot dry adiabats.

        Adds dry adiabats (lines of constant potential temperature) to the
        plot. The default style of these lines is dashed red lines with an alpha
        value of 0.5. These can be overridden using keyword arguments.

        Parameters
        ----------
        t0 : array_like, optional
            Starting temperature values in Kelvin. If none are given, they will be
            generated using the current temperature range at the bottom of
            the plot.
        p : array_like, optional
            Pressure values to be included in the dry adiabats. If not
            specified, they will be linearly distributed across the current
            plotted pressure range.
        kwargs
            Other keyword arguments to pass to :class:`matplotlib.collections.LineCollection`

        Returns
        -------
        matplotlib.collections.LineCollection
            instance created

        See Also
        --------
        :func:`~metpy.calc.thermo.dry_lapse`
        :meth:`plot_moist_adiabats`
        :class:`matplotlib.collections.LineCollection`
        """
        # Determine set of starting temps if necessary
        if t0 is None:
            xmin, xmax = self.ax.get_xlim()
            t0 = np.arange(xmin, xmax + 1, 10) * units.degC

        # Get pressure levels based on ylims if necessary
        if p is None:
            p = np.linspace(*self.ax.get_ylim()) * units.mbar

        # Assemble into data for plotting
        t = dry_lapse(p, t0[:, np.newaxis]).to(units.degC)
        linedata = [np.vstack((ti, p)).T for ti in t]

        # Add to plot
        kwargs.setdefault('colors', 'r')
        kwargs.setdefault('linestyles', 'dashed')
        kwargs.setdefault('alpha', 0.5)
        return self.ax.add_collection(LineCollection(linedata, **kwargs))

    def plot_moist_adiabats(self, t0=None, p=None, **kwargs):
        r"""Plot moist adiabats.

        Adds saturated pseudo-adiabats (lines of constant equivalent potential
        temperature) to the plot. The default style of these lines is dashed
        blue lines with an alpha value of 0.5. These can be overridden using
        keyword arguments.

        Parameters
        ----------
        t0 : array_like, optional
            Starting temperature values in Kelvin. If none are given, they will be
            generated using the current temperature range at the bottom of
            the plot.
        p : array_like, optional
            Pressure values to be included in the moist adiabats. If not
            specified, they will be linearly distributed across the current
            plotted pressure range.
        kwargs
            Other keyword arguments to pass to :class:`matplotlib.collections.LineCollection`

        Returns
        -------
        matplotlib.collections.LineCollection
            instance created

        See Also
        --------
        :func:`~metpy.calc.thermo.moist_lapse`
        :meth:`plot_dry_adiabats`
        :class:`matplotlib.collections.LineCollection`
        """
        # Determine set of starting temps if necessary
        if t0 is None:
            xmin, xmax = self.ax.get_xlim()
            t0 = np.concatenate((np.arange(xmin, 0, 10),
                                 np.arange(0, xmax + 1, 5))) * units.degC

        # Get pressure levels based on ylims if necessary
        if p is None:
            p = np.linspace(*self.ax.get_ylim()) * units.mbar

        # Assemble into data for plotting
        t = moist_lapse(p, t0[:, np.newaxis]).to(units.degC)
        linedata = [np.vstack((ti, p)).T for ti in t]

        # Add to plot
        kwargs.setdefault('colors', 'b')
        kwargs.setdefault('linestyles', 'dashed')
        kwargs.setdefault('alpha', 0.5)
        return self.ax.add_collection(LineCollection(linedata, **kwargs))

    def plot_mixing_lines(self, w=None, p=None, **kwargs):
        r"""Plot lines of constant mixing ratio.

        Adds lines of constant mixing ratio (isohumes) to the
        plot. The default style of these lines is dashed green lines with an
        alpha value of 0.8. These can be overridden using keyword arguments.

        Parameters
        ----------
        w : array_like, optional
            Unitless mixing ratio values to plot. If none are given, default
            values are used.
        p : array_like, optional
            Pressure values to be included in the isohumes. If not
            specified, they will be linearly distributed across the current
            plotted pressure range up to 600 mb.
        kwargs
            Other keyword arguments to pass to :class:`matplotlib.collections.LineCollection`

        Returns
        -------
        matplotlib.collections.LineCollection
            instance created

        See Also
        --------
        :class:`matplotlib.collections.LineCollection`
        """
        # Default mixing level values if necessary
        if w is None:
            w = np.array([0.0004, 0.001, 0.002, 0.004, 0.007, 0.01,
                          0.016, 0.024, 0.032]).reshape(-1, 1)

        # Set pressure range if necessary
        if p is None:
            p = np.linspace(600, max(self.ax.get_ylim())) * units.mbar

        # Assemble data for plotting
        td = dewpoint(vapor_pressure(p, w))
        linedata = [np.vstack((t, p)).T for t in td]

        # Add to plot
        kwargs.setdefault('colors', 'g')
        kwargs.setdefault('linestyles', 'dashed')
        kwargs.setdefault('alpha', 0.8)
        return self.ax.add_collection(LineCollection(linedata, **kwargs))


@exporter.export
class Hodograph(object):
    r"""Make a hodograph of wind data.

    Plots the u and v components of the wind along the x and y axes, respectively.

    This class simplifies the process of creating a hodograph using matplotlib.
    It provides helpers for creating a circular grid and for plotting the wind as a line
    colored by another value (such as wind speed).

    Attributes
    ----------
    ax : `matplotlib.axes.Axes`
        The underlying Axes instance used for all plotting
    """

    def __init__(self, ax=None, component_range=80):
        r"""Create a Hodograph instance.

        Parameters
        ----------
        ax : `matplotlib.axes.Axes`, optional
            The `Axes` instance used for plotting
        component_range : value
            The maximum range of the plot. Used to set plot bounds and control the maximum
            number of grid rings needed.
        """
        if ax is None:
            import matplotlib.pyplot as plt
            self.ax = plt.figure().add_subplot(1, 1, 1)
        else:
            self.ax = ax
        self.ax.set_aspect('equal', 'box')
        self.ax.set_xlim(-component_range, component_range)
        self.ax.set_ylim(-component_range, component_range)

        # == sqrt(2) * max_range, which is the distance at the corner
        self.max_range = 1.4142135 * component_range

    def add_grid(self, increment=10., **kwargs):
        r"""Add grid lines to hodograph.

        Creates lines for the x- and y-axes, as well as circles denoting wind speed values.

        Parameters
        ----------
        increment : value, optional
            The value increment between rings
        kwargs
            Other kwargs to control appearance of lines

        See Also
        --------
        :class:`matplotlib.patches.Circle`
        :meth:`matplotlib.axes.Axes.axhline`
        :meth:`matplotlib.axes.Axes.axvline`
        """
        # Some default arguments. Take those, and update with any
        # arguments passed in
        grid_args = dict(color='grey', linestyle='dashed')
        if kwargs:
            grid_args.update(kwargs)

        # Take those args and make appropriate for a Circle
        circle_args = grid_args.copy()
        color = circle_args.pop('color', None)
        circle_args['edgecolor'] = color
        circle_args['fill'] = False

        self.rings = []
        for r in np.arange(increment, self.max_range, increment):
            c = Circle((0, 0), radius=r, **circle_args)
            self.ax.add_patch(c)
            self.rings.append(c)

        # Add lines for x=0 and y=0
        self.yaxis = self.ax.axvline(0, **grid_args)
        self.xaxis = self.ax.axhline(0, **grid_args)

    @staticmethod
    def _form_line_args(kwargs):
        """Simplify taking the default line style and extending with kwargs."""
        def_args = dict(linewidth=3)
        def_args.update(kwargs)
        return def_args

    def plot(self, u, v, **kwargs):
        r"""Plot u, v data.

        Plots the wind data on the hodograph.

        Parameters
        ----------
        u : array_like
            u-component of wind
        v : array_like
            v-component of wind
        kwargs
            Other keyword arguments to pass to :meth:`matplotlib.axes.Axes.plot`

        Returns
        -------
        list[matplotlib.lines.Line2D]
            lines plotted

        See Also
        --------
        :meth:`Hodograph.plot_colormapped`
        """
        line_args = self._form_line_args(kwargs)
        u, v = delete_masked_points(u, v)
        return self.ax.plot(u, v, **line_args)

    def plot_colormapped(self, u, v, c, **kwargs):
        r"""Plot u, v data, with line colored based on a third set of data.

        Plots the wind data on the hodograph, but with a colormapped line.

        Simple wrapper around plot so that pressure is the first (independent)
        input. This is essentially a wrapper around `semilogy`. It also
        sets some appropriate ticking and plot ranges.

        Parameters
        ----------
        u : array_like
            u-component of wind
        v : array_like
            v-component of wind
        c : array_like
            data to use for colormapping
        kwargs
            Other keyword arguments to pass to :class:`matplotlib.collections.LineCollection`

        Returns
        -------
        matplotlib.collections.LineCollection
            instance created

        See Also
        --------
        :meth:`Hodograph.plot`
        """
        line_args = self._form_line_args(kwargs)
        u, v, c = delete_masked_points(u, v, c)
        lc = colored_line(u, v, c, **line_args)
        self.ax.add_collection(lc)
        return lc

Unidata / MetPy

Pull Request — master (#378)

SkewT.fill_betweenx() A

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