矩形选择

做一个鼠标点击某个地方，移动鼠标到某个目的地，释放按钮。该类提供单击和释放事件，还绘制一条线或一个框，从单击点到实际鼠标位置（在相同的轴内），直到按钮被释放。方法内 self.ignore() 检查eventpress和eventrelease的按钮是否相同。

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


def line_select_callback(eclick, erelease):
    """
    Callback for line selection.

    *eclick* and *erelease* are the press and release events.
    """
    x1, y1 = eclick.xdata, eclick.ydata
    x2, y2 = erelease.xdata, erelease.ydata
    print(f"({x1:3.2f}, {y1:3.2f}) --> ({x2:3.2f}, {y2:3.2f})")
    print(f" The buttons you used were: {eclick.button} {erelease.button}")


def toggle_selector(event):
    print(' Key pressed.')
    if event.key == 't':
        if toggle_selector.RS.active:
            print(' RectangleSelector deactivated.')
            toggle_selector.RS.set_active(False)
        else:
            print(' RectangleSelector activated.')
            toggle_selector.RS.set_active(True)


fig, ax = plt.subplots()
N = 100000  # If N is large one can see improvement by using blitting.
x = np.linspace(0, 10, N)

ax.plot(x, np.sin(2*np.pi*x))  # plot something
ax.set_title(
    "Click and drag to draw a rectangle.\n"
    "Press 't' to toggle the selector on and off.")

# drawtype is 'box' or 'line' or 'none'
toggle_selector.RS = RectangleSelector(ax, line_select_callback,
                                       drawtype='box', useblit=True,
                                       button=[1, 3],  # disable middle button
                                       minspanx=5, minspany=5,
                                       spancoords='pixels',
                                       interactive=True)
fig.canvas.mpl_connect('key_press_event', toggle_selector)
plt.show()