matplotlib绘制多子图共享鼠标光标的方法示例

matplotlib官方除了提供了鼠标十字光标的示例，还提供了同一图像内多子图共享光标的示例，其功能主要由widgets模块中的MultiCursor类提供支持。

MultiCursor类与Cursor类参数类似，差异主要在：

• Cursor类参数只有一个ax，即需要显示光标的子图；MultiCursor类参数为canvas和axes，其中axes为需要共享光标的子图列表。

• Cursor类中，光标默认是十字线；MultiCursor类中，光标默认为竖线。

官方示例

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.widgets import MultiCursor

t = np.arange(0.0, 2.0, 0.01)
s1 = np.sin(2*np.pi*t)
s2 = np.sin(4*np.pi*t)

fig, (ax1, ax2) = plt.subplots(2, sharex=True)
ax1.plot(t, s1)
ax2.plot(t, s2)

multi = MultiCursor(fig.canvas, (ax1, ax2), color='r', lw=1)
plt.show()

简易修改版

multi = MultiCursor(fig.canvas, (ax1, ax2), color='r', lw=1, horizOn=True, vertOn=True)

MultiCursor类源码

class MultiCursor(Widget):
 """
 Provide a vertical (default) and/or horizontal line cursor shared between
 multiple axes.

For the cursor to remain responsive you must keep a reference to it.

Example usage::

from matplotlib.widgets import MultiCursor
   import matplotlib.pyplot as plt
   import numpy as np

fig, (ax1, ax2) = plt.subplots(nrows=2, sharex=True)
   t = np.arange(0.0, 2.0, 0.01)
   ax1.plot(t, np.sin(2*np.pi*t))
   ax2.plot(t, np.sin(4*np.pi*t))

multi = MultiCursor(fig.canvas, (ax1, ax2), color='r', lw=1,
             horizOn=False, vertOn=True)
   plt.show()

"""
 def __init__(self, canvas, axes, useblit=True, horizOn=False, vertOn=True,
        **lineprops):

self.canvas = canvas
   self.axes = axes
   self.horizOn = horizOn
   self.vertOn = vertOn

xmin, xmax = axes[-1].get_xlim()
   ymin, ymax = axes[-1].get_ylim()
   xmid = 0.5 * (xmin + xmax)
   ymid = 0.5 * (ymin + ymax)

self.visible = True
   self.useblit = useblit and self.canvas.supports_blit
   self.background = None
   self.needclear = False

if self.useblit:
     lineprops['animated'] = True

if vertOn:
     self.vlines = [ax.axvline(xmid, visible=False, **lineprops)
             for ax in axes]
   else:
     self.vlines = []

if horizOn:
     self.hlines = [ax.axhline(ymid, visible=False, **lineprops)
             for ax in axes]
   else:
     self.hlines = []

self.connect()

def connect(self):
   """Connect events."""
   self._cidmotion = self.canvas.mpl_connect('motion_notify_event',
                        self.onmove)
   self._ciddraw = self.canvas.mpl_connect('draw_event', self.clear)

def disconnect(self):
   """Disconnect events."""
   self.canvas.mpl_disconnect(self._cidmotion)
   self.canvas.mpl_disconnect(self._ciddraw)

def clear(self, event):
   """Clear the cursor."""
   if self.ignore(event):
     return
   if self.useblit:
     self.background = (
       self.canvas.copy_from_bbox(self.canvas.figure.bbox))
   for line in self.vlines + self.hlines:
     line.set_visible(False)

def onmove(self, event):
   if self.ignore(event):
     return
   if event.inaxes is None:
     return
   if not self.canvas.widgetlock.available(self):
     return
   self.needclear = True
   if not self.visible:
     return
   if self.vertOn:
     for line in self.vlines:
       line.set_xdata((event.xdata, event.xdata))
       line.set_visible(self.visible)
   if self.horizOn:
     for line in self.hlines:
       line.set_ydata((event.ydata, event.ydata))
       line.set_visible(self.visible)
   self._update()

def _update(self):
   if self.useblit:
     if self.background is not None:
       self.canvas.restore_region(self.background)
     if self.vertOn:
       for ax, line in zip(self.axes, self.vlines):
         ax.draw_artist(line)
     if self.horizOn:
       for ax, line in zip(self.axes, self.hlines):
         ax.draw_artist(line)
     self.canvas.blit()
   else:
     self.canvas.draw_idle()

来源：https://blog.csdn.net/mighty13/article/details/112145863