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from __future__ import division, print_function, absolute_import
import numpy as np
from scipy._lib.decorator import decorator as _decorator
__all__ = ['delaunay_plot_2d', 'convex_hull_plot_2d', 'voronoi_plot_2d']
@_decorator
def _held_figure(func, obj, ax=None, **kw):
import matplotlib.pyplot as plt
if ax is None:
fig = plt.figure()
ax = fig.gca()
return func(obj, ax=ax, **kw)
# As of matplotlib 2.0, the "hold" mechanism is deprecated.
# When matplotlib 1.x is no longer supported, this check can be removed.
was_held = getattr(ax, 'ishold', lambda: True)()
if was_held:
return func(obj, ax=ax, **kw)
try:
ax.hold(True)
return func(obj, ax=ax, **kw)
finally:
ax.hold(was_held)
def _adjust_bounds(ax, points):
margin = 0.1 * points.ptp(axis=0)
xy_min = points.min(axis=0) - margin
xy_max = points.max(axis=0) + margin
ax.set_xlim(xy_min[0], xy_max[0])
ax.set_ylim(xy_min[1], xy_max[1])
@_held_figure
def delaunay_plot_2d(tri, ax=None):
"""
Plot the given Delaunay triangulation in 2-D
Parameters
----------
tri : scipy.spatial.Delaunay instance
Triangulation to plot
ax : matplotlib.axes.Axes instance, optional
Axes to plot on
Returns
-------
fig : matplotlib.figure.Figure instance
Figure for the plot
See Also
--------
Delaunay
matplotlib.pyplot.triplot
Notes
-----
Requires Matplotlib.
Examples
--------
>>> import matplotlib.pyplot as plt
>>> from scipy.spatial import Delaunay, delaunay_plot_2d
The Delaunay triangulation of a set of random points:
>>> points = np.random.rand(30, 2)
>>> tri = Delaunay(points)
Plot it:
>>> _ = delaunay_plot_2d(tri)
>>> plt.show()
"""
if tri.points.shape[1] != 2:
raise ValueError("Delaunay triangulation is not 2-D")
x, y = tri.points.T
ax.plot(x, y, 'o')
ax.triplot(x, y, tri.simplices.copy())
_adjust_bounds(ax, tri.points)
return ax.figure
@_held_figure
def convex_hull_plot_2d(hull, ax=None):
"""
Plot the given convex hull diagram in 2-D
Parameters
----------
hull : scipy.spatial.ConvexHull instance
Convex hull to plot
ax : matplotlib.axes.Axes instance, optional
Axes to plot on
Returns
-------
fig : matplotlib.figure.Figure instance
Figure for the plot
See Also
--------
ConvexHull
Notes
-----
Requires Matplotlib.
Examples
--------
>>> import matplotlib.pyplot as plt
>>> from scipy.spatial import ConvexHull, convex_hull_plot_2d
The convex hull of a random set of points:
>>> points = np.random.rand(30, 2)
>>> hull = ConvexHull(points)
Plot it:
>>> _ = convex_hull_plot_2d(hull)
>>> plt.show()
"""
from matplotlib.collections import LineCollection
if hull.points.shape[1] != 2:
raise ValueError("Convex hull is not 2-D")
ax.plot(hull.points[:,0], hull.points[:,1], 'o')
line_segments = [hull.points[simplex] for simplex in hull.simplices]
ax.add_collection(LineCollection(line_segments,
colors='k',
linestyle='solid'))
_adjust_bounds(ax, hull.points)
return ax.figure
@_held_figure
def voronoi_plot_2d(vor, ax=None, **kw):
"""
Plot the given Voronoi diagram in 2-D
Parameters
----------
vor : scipy.spatial.Voronoi instance
Diagram to plot
ax : matplotlib.axes.Axes instance, optional
Axes to plot on
show_points: bool, optional
Add the Voronoi points to the plot.
show_vertices : bool, optional
Add the Voronoi vertices to the plot.
line_colors : string, optional
Specifies the line color for polygon boundaries
line_width : float, optional
Specifies the line width for polygon boundaries
line_alpha: float, optional
Specifies the line alpha for polygon boundaries
point_size: float, optional
Specifies the size of points
Returns
-------
fig : matplotlib.figure.Figure instance
Figure for the plot
See Also
--------
Voronoi
Notes
-----
Requires Matplotlib.
Examples
--------
Set of point:
>>> import matplotlib.pyplot as plt
>>> points = np.random.rand(10,2) #random
Voronoi diagram of the points:
>>> from scipy.spatial import Voronoi, voronoi_plot_2d
>>> vor = Voronoi(points)
using `voronoi_plot_2d` for visualisation:
>>> fig = voronoi_plot_2d(vor)
using `voronoi_plot_2d` for visualisation with enhancements:
>>> fig = voronoi_plot_2d(vor, show_vertices=False, line_colors='orange',
... line_width=2, line_alpha=0.6, point_size=2)
>>> plt.show()
"""
from matplotlib.collections import LineCollection
if vor.points.shape[1] != 2:
raise ValueError("Voronoi diagram is not 2-D")
if kw.get('show_points', True):
point_size = kw.get('point_size', None)
ax.plot(vor.points[:,0], vor.points[:,1], '.', markersize=point_size)
if kw.get('show_vertices', True):
ax.plot(vor.vertices[:,0], vor.vertices[:,1], 'o')
line_colors = kw.get('line_colors', 'k')
line_width = kw.get('line_width', 1.0)
line_alpha = kw.get('line_alpha', 1.0)
center = vor.points.mean(axis=0)
ptp_bound = vor.points.ptp(axis=0)
finite_segments = []
infinite_segments = []
for pointidx, simplex in zip(vor.ridge_points, vor.ridge_vertices):
simplex = np.asarray(simplex)
if np.all(simplex >= 0):
finite_segments.append(vor.vertices[simplex])
else:
i = simplex[simplex >= 0][0] # finite end Voronoi vertex
t = vor.points[pointidx[1]] - vor.points[pointidx[0]] # tangent
t /= np.linalg.norm(t)
n = np.array([-t[1], t[0]]) # normal
midpoint = vor.points[pointidx].mean(axis=0)
direction = np.sign(np.dot(midpoint - center, n)) * n
far_point = vor.vertices[i] + direction * ptp_bound.max()
infinite_segments.append([vor.vertices[i], far_point])
ax.add_collection(LineCollection(finite_segments,
colors=line_colors,
lw=line_width,
alpha=line_alpha,
linestyle='solid'))
ax.add_collection(LineCollection(infinite_segments,
colors=line_colors,
lw=line_width,
alpha=line_alpha,
linestyle='dashed'))
_adjust_bounds(ax, vor.points)
return ax.figure
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