matplotlib & pandas

Python/matplotlab/gallery/misc/histogram_path.md

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+# 使用“矩形”和“多边形”构建直方图
+
+使用路径补丁绘制矩形。 使用大量Rectangle实例的技术或使用PolyCollections的更快方法是在我们在mpl中使用moveto / lineto，closepoly等的正确路径之前实现的。 现在我们拥有它们，我们可以使用PathCollection更有效地绘制具有同质属性的常规形状对象的集合。 这个例子创建了一个直方图 - 在开始时设置顶点数组的工作量更大，但对于大量对象来说它应该更快。
+
+```python
+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 = np.array(bins[:-1])
+right = np.array(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()
+```
+
+![使用“矩形”和“多边形”构建直方图示例](https://matplotlib.org/_images/sphx_glr_histogram_path_001.png)
+
+应该注意的是，我们可以使用顶点和代码直接创建复合路径，而不是创建三维数组并使用[make_compound_path_from_polys](https://matplotlib.org/api/path_api.html#matplotlib.path.Path.make_compound_path_from_polys)，如下所示
+
+```python
+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)
+```
+
+## 参考
+
+此示例中显示了以下函数，方法，类和模块的使用：
+
+```python
+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
+```
+
+## 下载这个示例
+            
+- [下载python源码: histogram_path.py](https://matplotlib.org/_downloads/histogram_path.py)
+- [下载Jupyter notebook: histogram_path.ipynb](https://matplotlib.org/_downloads/histogram_path.ipynb)