Hi,
We found we needed to draw a partial ring, but didn't see one in
patches.py.
Attached is a generalization of Wedge to accept an inner and an outer
radius.
Should I add this to patches?
Note that rather saving the unit ring and constructing a transform as
in Wedge:
def get_patch_transform(self):
x = self.convert_xunits(self.center[0])
y = self.convert_yunits(self.center[1])
rx = self.convert_xunits(self.r2)
ry = self.convert_yunits(self.r2)
self._patch_transform = transforms.Affine2D() \
.scale(rx, ry).translate(x, y)
return self._patch_transform
I just transform the coordinates directly:
v *= r2
v += numpy.array(center)
self._path = Path(v,c)
self._patch_transform = transforms.IdentityTransform()
Any reason to prefer one over the other?
- Paul
from math import fmod
import numpy
import matplotlib.cbook as cbook
import matplotlib.transforms as transforms
import matplotlib.artist as artist
import matplotlib.patches as patches
from matplotlib.path import Path
class Ring(patches.Patch):
"""
Ring patch.
"""
def __str__(self):
return "Ring(%g,%g,%g,%g)"%(self.r1,self.r2,self.theta1,self.theta2)
def __init__(self,
center=(0,0),
r1=0,
r2=None,
theta1=0,
theta2=360,
**kwargs
):
"""
Draw a ring centered at *x*, *y* center with inner radius *r1* and
outer radius *r2* that sweeps *theta1* to *theta2* (in degrees).
Valid kwargs are:
%(Patch)s
"""
patches.Patch.__init__(self, **kwargs)
self.center = center
self.r1, self.r2 = r1,r2
self.theta1, self.theta2 = theta1,theta2
# Inner and outer rings are connected unless the annulus is complete
delta=abs(theta2-theta1)
if fmod(delta,360)<=1e-12*delta:
theta1,theta2 = 0,360
connector = Path.MOVETO
else:
connector = Path.LINETO
# Form the outer ring
arc = Path.arc(theta1,theta2)
if r1 > 0:
# Partial annulus needs to draw the outter ring
# followed by a reversed and scaled inner ring
v1 = arc.vertices
v2 = arc.vertices[::-1]*float(r1)/r2
v = numpy.vstack([v1,v2,v1[0,:],(0,0)])
c = numpy.hstack([arc.codes,arc.codes,connector,Path.CLOSEPOLY])
c[len(arc.codes)]=connector
else:
# Wedge doesn't need an inner ring
v = numpy.vstack([arc.vertices,[(0,0),arc.vertices[0,:],(0,0)]])
c = numpy.hstack([arc.codes,[connector,connector,Path.CLOSEPOLY]])
v *= r2
v += numpy.array(center)
self._path = Path(v,c)
self._patch_transform = transforms.IdentityTransform()
__init__.__doc__ = cbook.dedent(__init__.__doc__) % artist.kwdocd
def get_path(self):
return self._path
def demo():
import pylab
axes = pylab.gca()
# Full ring
axes.add_patch(Ring(center=(3,3),r1=4, r2=7,theta1=70,theta2=70,
fill=True,fc='yellow',ec='darkblue',alpha=0.5))
# Full circle
axes.add_patch(Ring(center=(-3,-3),r2=4,
fill=True,fc='purple',ec='darkblue',alpha=0.6))
# Filled segment
axes.add_patch(Ring(r1=5,r2=10,theta1=0,theta2=90,
fill=True,fc='gray',ec='black',alpha=0.2))
# Unfilled segment
axes.add_patch(Ring(r1=6,r2=8,theta1=30,theta2=280,fill=False,ec='black'))
# Overlapping segment
axes.add_patch(Ring(r1=3,r2=9,theta1=80,theta2=130,
fill=True,fc='orange',ec='black',alpha=0.2))
# Unfilled wedge
axes.add_patch(Ring(r2=7,theta1=170,theta2=220,
fill=False,fc='orange',ec='green',alpha=0.2))
# Wedge
axes.add_patch(Ring(r2=7,theta1=70,theta2=220,
fill=False,fc='blue',ec='darkblue',alpha=0.6))
# # Wedge
# from matplotlib.patches import Wedge
# axes.add_patch(Wedge((0,0),r=7,theta1=70,theta2=220,
# fill=False,fc='blue',ec='darkblue',alpha=0.6))
pylab.axis('equal')
# pylab.axis([-10,10,-10,10])
pylab.show()
if __name__ == "__main__": demo()
One problem is that I had to explicitly set the axes limits 1because
add_patch
wasn't updating the limits to include the bounds of the new patch.
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