Matplotlib：用鼠标绘制矩形形状的选择区域

Question

我希望能够通过鼠标事件在 matplotlib 图上绘制选择区域。我没有找到有关如何使用 python 执行此操作的信息。

最后，我希望能够在使用 matplotlib 底图创建的地图上用鼠标绘制感兴趣区域并检索角坐标。

有人有想法、例子、参考吗？

谢谢，

格雷格

class Annotate(object):
  def __init__(self):
      self.ax = plt.gca()
      self.rect = Rectangle((0,0), 1, 1, facecolor='None', edgecolor='green')
      self.x0 = None
      self.y0 = None
      self.x1 = None
      self.y1 = None
      self.ax.add_patch(self.rect)
      self.ax.figure.canvas.mpl_connect('button_press_event', self.on_press)
      self.ax.figure.canvas.mpl_connect('button_release_event', self.on_release)
      self.ax.figure.canvas.mpl_connect('motion_notify_event', self.on_motion)
  def on_press(self, event):
      print 'press'
      self.x0 = event.xdata
      self.y0 = event.ydata    
      self.x1 = event.xdata
      self.y1 = event.ydata
      self.rect.set_width(self.x1 - self.x0)
      self.rect.set_height(self.y1 - self.y0)
      self.rect.set_xy((self.x0, self.y0))
      self.rect.set_linestyle('dashed')
      self.ax.figure.canvas.draw()
  def on_motion(self,event):
      if self.on_press is True:
          return
      self.x1 = event.xdata
      self.y1 = event.ydata
      self.rect.set_width(self.x1 - self.x0)
      self.rect.set_height(self.y1 - self.y0)
      self.rect.set_xy((self.x0, self.y0))
      self.rect.set_linestyle('dashed')
      self.ax.figure.canvas.draw()
  def on_release(self, event):
      print 'release'
      self.x1 = event.xdata
      self.y1 = event.ydata
      self.rect.set_width(self.x1 - self.x0)
      self.rect.set_height(self.y1 - self.y0)
      self.rect.set_xy((self.x0, self.y0))
      self.rect.set_linestyle('solid')
      self.ax.figure.canvas.draw()
      print self.x0,self.x1,self.y0,self.y1
      return [self.x0,self.x1,self.y0,self.y1]

Answer 1

这是一个小例子，展示了如何使用鼠标在 matplotlib 图上绘制一个矩形。

import matplotlib.pyplot as plt
from matplotlib.patches import Rectangle

class Annotate(object):
    def __init__(self):
        self.ax = plt.gca()
        self.rect = Rectangle((0,0), 1, 1)
        self.x0 = None
        self.y0 = None
        self.x1 = None
        self.y1 = None
        self.ax.add_patch(self.rect)
        self.ax.figure.canvas.mpl_connect('button_press_event', self.on_press)
        self.ax.figure.canvas.mpl_connect('button_release_event', self.on_release)

    def on_press(self, event):
        print 'press'
        self.x0 = event.xdata
        self.y0 = event.ydata

    def on_release(self, event):
        print 'release'
        self.x1 = event.xdata
        self.y1 = event.ydata
        self.rect.set_width(self.x1 - self.x0)
        self.rect.set_height(self.y1 - self.y0)
        self.rect.set_xy((self.x0, self.y0))
        self.ax.figure.canvas.draw()

a = Annotate()
plt.show()

Answer 2

Matplotlib 提供了自己的RectangleSelector。 matplotlib 页面上有an example，您可以根据自己的需要进行调整。

简化版如下所示：

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

xdata = np.linspace(0,9*np.pi, num=301)
ydata = np.sin(xdata)

fig, ax = plt.subplots()
line, = ax.plot(xdata, ydata)


def line_select_callback(eclick, erelease):
    x1, y1 = eclick.xdata, eclick.ydata
    x2, y2 = erelease.xdata, erelease.ydata

    rect = plt.Rectangle( (min(x1,x2),min(y1,y2)), np.abs(x1-x2), np.abs(y1-y2) )
    ax.add_patch(rect)


rs = RectangleSelector(ax, line_select_callback,
                       drawtype='box', useblit=False, button=[1], 
                       minspanx=5, minspany=5, spancoords='pixels', 
                       interactive=True)

plt.show()