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# Copyright (c) 2008-2015 MetPy Developers. |
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# Distributed under the terms of the BSD 3-Clause License. |
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# SPDX-License-Identifier: BSD-3-Clause |
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"""Utilities for use in making plots.""" |
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from datetime import datetime |
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import os |
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from matplotlib.collections import LineCollection |
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from matplotlib.pyplot import imread |
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import numpy as np |
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from ..units import concatenate |
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def add_timestamp(ax, time=None, x=0.99, y=-0.04, ha='right', **kwargs): |
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"""Add a timestamp at plot creation time. |
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Adds an ISO format timestamp with the time of plot creation to the plot. |
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Parameters |
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---------- |
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ax : `matplotlib.axes.Axes` |
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The `Axes` instance used for plotting |
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time : `datetime.datetime` |
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Specific time to be plotted - datetime.utcnow will be use if not specified |
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x : float |
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Relative x position on the axes of the timestamp |
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y : float |
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Relative y position on the axes of the timestamp |
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ha : str |
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Horizontal alignment of the time stamp string |
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Returns |
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------- |
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ax : `matplotlib.axes.Axes` |
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The `Axes` instance used for plotting |
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""" |
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if not time: |
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time = datetime.utcnow() |
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timestr = datetime.strftime(time, 'Created: %Y-%m-%dT%H:%M:%SZ') |
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ax.text(x, y, timestr, ha=ha, transform=ax.transAxes, **kwargs) |
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return ax |
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def add_logo(fig, x=10, y=25, zorder=100, size='small', **kwargs): |
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"""Add the MetPy logo to a figure. |
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Adds an image of the MetPy logo to the figure. |
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Parameters |
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---------- |
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fig : `matplotlib.figure` |
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The `figure` instance used for plotting |
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x : int |
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x position padding in pixels |
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y : float |
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y position padding in pixels |
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zorder : int |
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The zorder of the logo |
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size : str |
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Size of logo to be used. Can be 'small' for 75 px square or 'large' for |
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150 px square. |
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Returns |
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------- |
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fig : `matplotlib.figure` |
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The `figure` instance used for plotting |
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""" |
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fnames = {'small': 'metpy_75x75.png', |
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'large': 'metpy_150x150.png'} |
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try: |
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metpy_logo = imread(os.path.join(os.path.dirname(__file__), '_static', fnames[size])) |
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except KeyError: |
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raise ValueError('Unknown option for size: {0}'.format(str(size))) |
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fig.figimage(metpy_logo, x, y, zorder=zorder, **kwargs) |
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return fig |
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# Not part of public API |
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def colored_line(x, y, c, **kwargs): |
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"""Create a multi-colored line. |
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Takes a set of points and turns them into a collection of lines colored by another array. |
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Parameters |
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---------- |
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x : array-like |
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x-axis coordinates |
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y : array-like |
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y-axis coordinates |
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c : array-like |
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values used for color-mapping |
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kwargs : dict |
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Other keyword arguments passed to :class:`matplotlib.collections.LineCollection` |
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Returns |
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------- |
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The created :class:`matplotlib.collections.LineCollection` instance. |
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""" |
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# Mask out any NaN values |
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nan_mask = ~(np.isnan(x) | np.isnan(y) | np.isnan(c)) |
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x = x[nan_mask] |
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y = y[nan_mask] |
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c = c[nan_mask] |
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# Paste values end to end |
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points = concatenate([x, y]) |
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# Exploit numpy's strides to present a view of these points without copying. |
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# Dimensions are (segment, start/end, x/y). Since x and y are concatenated back to back, |
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# moving between segments only moves one item; moving start to end is only an item; |
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# The move between x any moves from one half of the array to the other |
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num_pts = points.size // 2 |
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final_shape = (num_pts - 1, 2, 2) |
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final_strides = (points.itemsize, points.itemsize, num_pts * points.itemsize) |
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segments = np.lib.stride_tricks.as_strided(points, shape=final_shape, |
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strides=final_strides) |
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# Create a LineCollection from the segments and set it to colormap based on c |
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lc = LineCollection(segments, **kwargs) |
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lc.set_array(c) |
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return lc |
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Unidata /
MetPy
