Python库matplotlib之十

Python库matplotlib之十

• 事件处理
• • 关闭活动
  • 鼠标移动和点击事件
  • 按键事件

事件处理

关闭活动

下列代码，当用户点击关闭窗口时，调用关闭回调函数on_close。这给程序员在窗口关闭之前，做一些cleanup工作， 比如，关闭文件，TCP/IP端口等。

import matplotlib.pyplot as plt
import pandas as pd
import numpy as np

delta = 0

def on_close(event):
    print('Closed Figure!')

def update_draw(axes):
    global x, y, delta
    y = np.sin(x + delta)
    line.set_ydata(y)
    axes.figure.canvas.draw()
    delta += 10

if __name__ == "__main__":
    global x, y
    fig, ax = plt.subplots()
    fig.canvas.mpl_connect('close_event', on_close)
    x = np.linspace(0, 10 * np.pi, 100)
    y = np.sin(x)
    line, = plt.plot(x, y);
    
    timer = fig.canvas.new_timer(interval=100)
    timer.add_callback(update_draw, ax)
    timer.start()
    
    plt.show()

程序运行输出屏幕

C:\>python event_handle_1.py
Closed Figure!

鼠标移动和点击事件

下列的例子通过连接移动和单击事件与绘图画布进行交互的例子。

下列运行时，当用户点击鼠标的左键，一条竖线随鼠标移动；当用户点击右键时，竖线停止移动。再次点击左键，竖线再次随鼠标移动。

import matplotlib.pyplot as plt
import numpy as np

from matplotlib.backend_bases import MouseButton

def on_move(event):
    global fig, ax, t, s
    if event.inaxes:
        ax.clear()
        x = [event.xdata, event.xdata]
        y = [0, event.ydata]
        ax.plot(x, y)
        line, = ax.plot(t, s)
        fig.canvas.draw()
        
def on_click(event):
    global binding_id
    if event.button is MouseButton.LEFT:
        print('disconnecting callback')
        plt.disconnect(binding_id)
    elif event.button is MouseButton.RIGHT:
        print('connecting callback')
        binding_id = plt.connect('motion_notify_event', on_move)

if __name__ == "__main__":
    global fig, ax, t, s, binding_id
    t = np.arange(0.0, 1.0, 0.01)
    s = np.sin(2 * np.pi * t)
    fig, ax = plt.subplots()
    line, = ax.plot(t, s)

    binding_id = plt.connect('motion_notify_event', on_move)
    plt.connect('button_press_event', on_click)
    
    plt.show()

程序运行屏幕输出

C:\>python event_handle_2.py
disconnecting callback
connecting callback
disconnecting callback
connecting callback
disconnecting callback
connecting callback
disconnecting callback
connecting callback
disconnecting callback

按键事件

下列程序检测四个键x,y,+ 和 -。x和y改变正弦曲线的画线方式和颜色， +和-改变正弦曲线的相位角。

import sys
import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(0, 10 * np.pi, 100)
y = np.sin(x)

linestyle = ["-.","-", ":"]
colors = ["b","r","g"]
linestyle_ndx = 0
delta = 0
color_ndx = 0

def on_press(event):
    global linestyle, linestyle_ndx, line, x, y, delta, ax, color_ndx
    if event.key == 'x':
        line.set_linestyle(linestyle[linestyle_ndx])
        y = np.sin(x+delta)
        line.set_ydata(y)
        linestyle_ndx += 1
        if linestyle_ndx >= len(linestyle):
            linestyle_ndx = 0
        fig.canvas.draw()
    if event.key == 'y':
        line.set_color(colors[color_ndx])
        y = np.sin(x+delta)
        line.set_ydata(y)
        color_ndx += 1
        if color_ndx >= len(colors):
            color_ndx = 0
        fig.canvas.draw()
    elif event.key == '+':
        delta += 10
        y = np.sin(x+delta)
        line.set_ydata(y)
        ax.set_xlabel('delta = ' + str(delta))
        fig.canvas.draw()
    elif event.key == '-':
        delta -= 10
        if delta < 0:
            delta = 0
        y = np.sin(x+delta)
        line.set_ydata(y)
        fig.canvas.draw()
        xl = ax.set_xlabel('delta = ' + str(delta))
        fig.canvas.draw()

if __name__ == "__main__":
    # Fixing random state for reproducibility
    global fig, ax, line
    fig, ax = plt.subplots()

    fig.canvas.mpl_connect('key_press_event', on_press)
    #line, = ax.plot(x, y, linestyle[linestyle_ndx])

    line, = ax.plot(x, y, 'b-.')
    ax.set_title('Press X')
    plt.show()