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two new examples using a compund path for a histogram; one animated
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""" | ||
This example shows how to use a path patch to draw a bunch of | ||
rectangles. The technique of using lots of Rectangle instances, or | ||
the faster method of using PolyCollections, were implemented before we | ||
had proper paths with moveto/lineto, closepoly etc in mpl. Now that | ||
we have them, we can draw collections of regularly shaped objects with | ||
homogeous properties more efficiently with a PathCollection. This | ||
example makes a histogram -- its more work to set up the vertex arrays | ||
at the outset, but it should be much faster for large numbers of | ||
objects | ||
""" | ||
import time | ||
import numpy as np | ||
import matplotlib | ||
matplotlib.use('TkAgg') # do this before importing pylab | ||
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import matplotlib.pyplot as plt | ||
import matplotlib.patches as patches | ||
import matplotlib.path as path | ||
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fig = plt.figure() | ||
ax = fig.add_subplot(111) | ||
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# histogram our data with numpy | ||
data = np.random.randn(1000) | ||
n, bins = np.histogram(data, 100) | ||
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# get the corners of the rectangles for the histogram | ||
left = np.array(bins[:-1]) | ||
right = np.array(bins[1:]) | ||
bottom = np.zeros(len(left)) | ||
top = bottom + n | ||
nrects = len(left) | ||
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# here comes the tricky part -- we have to set up the vertex and path | ||
# codes arrays using moveto, lineto and closepoly | ||
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# for each rect: 1 for the MOVETO, 3 for the LINETO, 1 for the | ||
# CLOSEPOLY; the vert for the closepoly is ignored but we still need | ||
# it to keep the codes aligned with the vertices | ||
nverts = nrects*(1+3+1) | ||
verts = np.zeros((nverts, 2)) | ||
codes = np.ones(nverts, int) * path.Path.LINETO | ||
codes[0::5] = path.Path.MOVETO | ||
codes[4::5] = path.Path.CLOSEPOLY | ||
verts[0::5,0] = left | ||
verts[0::5,1] = bottom | ||
verts[1::5,0] = left | ||
verts[1::5,1] = top | ||
verts[2::5,0] = right | ||
verts[2::5,1] = top | ||
verts[3::5,0] = right | ||
verts[3::5,1] = bottom | ||
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barpath = path.Path(verts, codes) | ||
patch = patches.PathPatch(barpath, facecolor='green', edgecolor='yellow', alpha=0.5) | ||
ax.add_patch(patch) | ||
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ax.set_xlim(left[0], right[-1]) | ||
ax.set_ylim(bottom.min(), top.max()) | ||
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def animate(): | ||
tstart = time.time() # for profiling | ||
# simulate new data coming in | ||
data = np.random.randn(1000) | ||
n, bins = np.histogram(data, 100) | ||
top = bottom + n | ||
verts[1::5,1] = top | ||
verts[2::5,1] = top | ||
fig.canvas.draw() | ||
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def run(): | ||
for i in range(100): | ||
fig.canvas.manager.window.after(100, animate) | ||
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fig.canvas.manager.window.after(100, run) | ||
plt.show() |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,59 @@ | ||
""" | ||
This example shows how to use a path patch to draw a bunch of | ||
rectangles. The technique of using lots of Rectangle instances, or | ||
the faster method of using PolyCollections, were implemented before we | ||
had proper paths with moveto/lineto, closepoly etc in mpl. Now that | ||
we have them, we can draw collections of regularly shaped objects with | ||
homogeous properties more efficiently with a PathCollection. This | ||
example makes a histogram -- its more work to set up the vertex arrays | ||
at the outset, but it should be much faster for large numbers of | ||
objects | ||
""" | ||
|
||
import numpy as np | ||
import matplotlib.pyplot as plt | ||
import matplotlib.patches as patches | ||
import matplotlib.path as path | ||
|
||
fig = plt.figure() | ||
ax = fig.add_subplot(111) | ||
|
||
# histogram our data with numpy | ||
data = np.random.randn(1000) | ||
n, bins = np.histogram(data, 100) | ||
|
||
# get the corners of the rectangles for the histogram | ||
left = np.array(bins[:-1]) | ||
right = np.array(bins[1:]) | ||
bottom = np.zeros(len(left)) | ||
top = bottom + n | ||
nrects = len(left) | ||
|
||
# here comes the tricky part -- we have to set up the vertex and path | ||
# codes arrays using moveto, lineto and closepoly | ||
|
||
# for each rect: 1 for the MOVETO, 3 for the LINETO, 1 for the | ||
# CLOSEPOLY; the vert for the closepoly is ignored but we still need | ||
# it to keep the codes aligned with the vertices | ||
nverts = nrects*(1+3+1) | ||
verts = np.zeros((nverts, 2)) | ||
codes = np.ones(nverts, int) * path.Path.LINETO | ||
codes[0::5] = path.Path.MOVETO | ||
codes[4::5] = path.Path.CLOSEPOLY | ||
verts[0::5,0] = left | ||
verts[0::5,1] = bottom | ||
verts[1::5,0] = left | ||
verts[1::5,1] = top | ||
verts[2::5,0] = right | ||
verts[2::5,1] = top | ||
verts[3::5,0] = right | ||
verts[3::5,1] = bottom | ||
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barpath = path.Path(verts, codes) | ||
patch = patches.PathPatch(barpath, facecolor='green', edgecolor='yellow', alpha=0.5) | ||
ax.add_patch(patch) | ||
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ax.set_xlim(left[0], right[-1]) | ||
ax.set_ylim(bottom.min(), top.max()) | ||
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plt.show() |