矩形和椭圆选择器

单击某处，移动鼠标，然后松开鼠标按钮。 RectangleSelector并EllipseSelector从初始单击位置到当前鼠标位置（在同一轴内）绘制一个矩形或椭圆形，直到释放按钮。连接的回调接收点击和释放事件。

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


def 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':
        for selector in selectors:
            name = type(selector).__name__
            if selector.active:
                print(f'{name} deactivated.')
                selector.set_active(False)
            else:
                print(f'{name} activated.')
                selector.set_active(True)


fig = plt.figure(constrained_layout=True)
axs = fig.subplots(2)

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

selectors = []
for ax, selector_class in zip(axs, [RectangleSelector, EllipseSelector]):
    ax.plot(x, np.sin(2*np.pi*x))  # plot something
    ax.set_title(f"Click and drag to draw a {selector_class.__name__}.")
    selectors.append(selector_class(
        ax, select_callback,
        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)
axs[0].set_title("Press 't' to toggle the selectors on and off.\n"
                 + axs[0].get_title())
plt.show()

参考

此示例中显示了以下函数、方法、类和模块的使用：

• matplotlib.widgets.RectangleSelector

• matplotlib.widgets.EllipseSelector