使用矩形和多集合构建柱状图

使用路径修补程序绘制矩形。在MPL中使用moveto/lineto、closepoly等适当路径之前，实现了使用大量矩形实例的技术，或使用多集合的更快方法。现在我们有了它们，就可以用PathCollection更有效地绘制具有同构属性的规则形状对象的集合。这个例子制作了一个柱状图——在开始时设置顶点数组的工作更多，但是对于大量的对象来说应该更快。

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches
import matplotlib.path as path

fig, ax = plt.subplots()

# Fixing random state for reproducibility
np.random.seed(19680801)


# histogram our data with numpy

data = np.random.randn(1000)
n, bins = np.histogram(data, 50)

# get the corners of the rectangles for the histogram
left = bins[:-1]
right = bins[1:]
bottom = np.zeros(len(left))
top = bottom + n


# we need a (numrects x numsides x 2) numpy array for the path helper
# function to build a compound path
XY = np.array([[left, left, right, right], [bottom, top, top, bottom]]).T

# get the Path object
barpath = path.Path.make_compound_path_from_polys(XY)

# make a patch out of it
patch = patches.PathPatch(barpath)
ax.add_patch(patch)

# update the view limits
ax.set_xlim(left[0], right[-1])
ax.set_ylim(bottom.min(), top.max())

plt.show()

应该注意的是，不要创建三维数组，而是使用 make_compound_path_from_polys 我们还可以直接使用顶点和代码创建复合路径，如下所示

nrects = len(left)
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

barpath = path.Path(verts, codes)

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工具书类

以下函数、方法、类和模块的使用如本例所示：

import matplotlib
matplotlib.patches
matplotlib.patches.PathPatch
matplotlib.path
matplotlib.path.Path
matplotlib.path.Path.make_compound_path_from_polys
matplotlib.axes.Axes.add_patch
matplotlib.collections.PathCollection

# This example shows an alternative to
matplotlib.collections.PolyCollection
matplotlib.axes.Axes.hist

出：

<function Axes.hist at 0x7faa00dc7f28>