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Python

"""
Testing that skewed axes properly work.
"""
from contextlib import ExitStack
import itertools
import matplotlib.pyplot as plt
from matplotlib.testing.decorators import image_comparison
from matplotlib.axes import Axes
import matplotlib.transforms as transforms
import matplotlib.axis as maxis
import matplotlib.spines as mspines
import matplotlib.patches as mpatch
from matplotlib.projections import register_projection
# The sole purpose of this class is to look at the upper, lower, or total
# interval as appropriate and see what parts of the tick to draw, if any.
class SkewXTick(maxis.XTick):
def draw(self, renderer):
with ExitStack() as stack:
for artist in [self.gridline, self.tick1line, self.tick2line,
self.label1, self.label2]:
stack.callback(artist.set_visible, artist.get_visible())
needs_lower = transforms.interval_contains(
self.axes.lower_xlim, self.get_loc())
needs_upper = transforms.interval_contains(
self.axes.upper_xlim, self.get_loc())
self.tick1line.set_visible(
self.tick1line.get_visible() and needs_lower)
self.label1.set_visible(
self.label1.get_visible() and needs_lower)
self.tick2line.set_visible(
self.tick2line.get_visible() and needs_upper)
self.label2.set_visible(
self.label2.get_visible() and needs_upper)
super(SkewXTick, self).draw(renderer)
def get_view_interval(self):
return self.axes.xaxis.get_view_interval()
# This class exists to provide two separate sets of intervals to the tick,
# as well as create instances of the custom tick
class SkewXAxis(maxis.XAxis):
def _get_tick(self, major):
return SkewXTick(self.axes, None, '', major=major)
def get_view_interval(self):
return self.axes.upper_xlim[0], self.axes.lower_xlim[1]
# This class exists to calculate the separate data range of the
# upper X-axis and draw the spine there. It also provides this range
# to the X-axis artist for ticking and gridlines
class SkewSpine(mspines.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
# This class handles registration of the skew-xaxes as a projection as well
# as setting up the appropriate transformations. It also overrides standard
# spines and axes instances as appropriate.
class SkewXAxes(Axes):
# 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_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):
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):
"""
This is called once when the plot is created to set up all the
transforms for the data, text and grids.
"""
rot = 30
# 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(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(rot, 0)) + self.transAxes
@property
def lower_xlim(self):
return self.axes.viewLim.intervalx
@property
def upper_xlim(self):
pts = [[0., 1.], [1., 1.]]
return self.transDataToAxes.inverted().transform(pts)[:, 0]
# Now register the projection with matplotlib so the user can select
# it.
register_projection(SkewXAxes)
@image_comparison(['skew_axes'], remove_text=True)
def test_set_line_coll_dash_image():
fig = plt.figure()
ax = fig.add_subplot(1, 1, 1, projection='skewx')
ax.set_xlim(-50, 50)
ax.set_ylim(50, -50)
ax.grid(True)
# An example of a slanted line at constant X
ax.axvline(0, color='b')
@image_comparison(['skew_rects'], remove_text=True)
def test_skew_rectangle():
fix, axes = plt.subplots(5, 5, sharex=True, sharey=True, figsize=(8, 8))
axes = axes.flat
rotations = list(itertools.product([-3, -1, 0, 1, 3], repeat=2))
axes[0].set_xlim([-3, 3])
axes[0].set_ylim([-3, 3])
axes[0].set_aspect('equal', share=True)
for ax, (xrots, yrots) in zip(axes, rotations):
xdeg, ydeg = 45 * xrots, 45 * yrots
t = transforms.Affine2D().skew_deg(xdeg, ydeg)
ax.set_title('Skew of {0} in X and {1} in Y'.format(xdeg, ydeg))
ax.add_patch(mpatch.Rectangle([-1, -1], 2, 2,
transform=t + ax.transData,
alpha=0.5, facecolor='coral'))
plt.subplots_adjust(wspace=0, left=0.01, right=0.99, bottom=0.01, top=0.99)