matplotlib & pandas

Python/matplotlab/gallery/event_handling/legend_picking.md

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+# 图例选择
+
+启用图例上的拾取以打开和关闭原始线。
+
+![图例选择](https://matplotlib.org/_images/sphx_glr_legend_picking_001.png)
+
+```python
+import numpy as np
+import matplotlib.pyplot as plt
+
+t = np.arange(0.0, 0.2, 0.1)
+y1 = 2*np.sin(2*np.pi*t)
+y2 = 4*np.sin(2*np.pi*2*t)
+
+fig, ax = plt.subplots()
+ax.set_title('Click on legend line to toggle line on/off')
+line1, = ax.plot(t, y1, lw=2, color='red', label='1 HZ')
+line2, = ax.plot(t, y2, lw=2, color='blue', label='2 HZ')
+leg = ax.legend(loc='upper left', fancybox=True, shadow=True)
+leg.get_frame().set_alpha(0.4)
+
+
+# we will set up a dict mapping legend line to orig line, and enable
+# picking on the legend line
+lines = [line1, line2]
+lined = dict()
+for legline, origline in zip(leg.get_lines(), lines):
+    legline.set_picker(5)  # 5 pts tolerance
+    lined[legline] = origline
+
+
+def onpick(event):
+    # on the pick event, find the orig line corresponding to the
+    # legend proxy line, and toggle the visibility
+    legline = event.artist
+    origline = lined[legline]
+    vis = not origline.get_visible()
+    origline.set_visible(vis)
+    # Change the alpha on the line in the legend so we can see what lines
+    # have been toggled
+    if vis:
+        legline.set_alpha(1.0)
+    else:
+        legline.set_alpha(0.2)
+    fig.canvas.draw()
+
+fig.canvas.mpl_connect('pick_event', onpick)
+
+plt.show()
+```
+
+## 下载这个示例
+            
+- [下载python源码: legend_picking.py](https://matplotlib.org/_downloads/legend_picking.py)
+- [下载Jupyter notebook: legend_picking.ipynb](https://matplotlib.org/_downloads/legend_picking.ipynb)