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89 lines
2.8 KiB
Markdown
89 lines
2.8 KiB
Markdown
# 动画直方图
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使用路径补丁为动画直方图绘制一堆矩形。
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```python
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import numpy as np
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import matplotlib.pyplot as plt
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import matplotlib.patches as patches
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import matplotlib.path as path
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import matplotlib.animation as animation
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# Fixing random state for reproducibility
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np.random.seed(19680801)
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# histogram our data with numpy
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data = np.random.randn(1000)
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n, bins = np.histogram(data, 100)
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# get the corners of the rectangles for the histogram
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left = np.array(bins[:-1])
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right = np.array(bins[1:])
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bottom = np.zeros(len(left))
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top = bottom + n
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nrects = len(left)
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```
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这里有一个棘手的部分 - 我们必须为每个rect使用 ``plt.Path.MOVETO``，``plt.Path.LINETO``和``plt.Path.CLOSEPOLY``设置顶点和路径代码数组。
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- 每个矩形我们需要1个 ``MOVETO``，它设置了初始点。
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- 我们需要3个``LINETO``，它告诉Matplotlib从顶点1到顶点2，v2到v3和v3到v4绘制线。
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- 然后我们需要一个``CLOSEPOLY``，它告诉Matplotlib从v4到我们的初始顶点（MOVETO顶点）绘制一条线，以便关闭多边形。
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**注意：**CLOSEPOLY的顶点被忽略，但我们仍然需要在verts数组中使用占位符来保持代码与顶点对齐。
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```python
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nverts = nrects * (1 + 3 + 1)
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verts = np.zeros((nverts, 2))
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codes = np.ones(nverts, int) * path.Path.LINETO
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codes[0::5] = path.Path.MOVETO
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codes[4::5] = path.Path.CLOSEPOLY
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verts[0::5, 0] = left
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verts[0::5, 1] = bottom
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verts[1::5, 0] = left
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verts[1::5, 1] = top
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verts[2::5, 0] = right
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verts[2::5, 1] = top
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verts[3::5, 0] = right
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verts[3::5, 1] = bottom
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```
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为了给直方图设置动画，我们需要一个动画函数，它生成一组随机数字并更新直方图顶点的位置（在这种情况下，只有每个矩形的高度）。 补丁最终将成为补丁对象。
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```python
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patch = None
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def animate(i):
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# simulate new data coming in
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data = np.random.randn(1000)
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n, bins = np.histogram(data, 100)
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top = bottom + n
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verts[1::5, 1] = top
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verts[2::5, 1] = top
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return [patch, ]
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```
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现在我们使用顶点和代码为直方图构建Path和Patch实例。 我们将补丁添加到Axes实例，并使用我们的animate函数设置``FuncAnimation``。
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```python
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fig, ax = plt.subplots()
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barpath = path.Path(verts, codes)
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patch = patches.PathPatch(
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barpath, facecolor='green', edgecolor='yellow', alpha=0.5)
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ax.add_patch(patch)
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ax.set_xlim(left[0], right[-1])
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ax.set_ylim(bottom.min(), top.max())
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ani = animation.FuncAnimation(fig, animate, 100, repeat=False, blit=True)
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plt.show()
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```
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## 下载这个示例
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- [下载python源码: animated_histogram.py](https://matplotlib.org/_downloads/animated_histogram.py)
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- [下载Jupyter notebook: animated_histogram.ipynb](https://matplotlib.org/_downloads/animated_histogram.ipynb) |