Python:Matplotlib 按钮不工作

Question

我的这段代码包含一个名为 bbutton 的按钮，按下该按钮会执行 movetext 功能:

from pylab import *
from matplotlib.widgets import  RectangleSelector
from matplotlib.widgets import Button
import numpy as np
import matplotlib.pylab as plt


fig = plt.figure()
ax = fig.add_subplot(111)

delta = 0.025
x = np.arange(-3.0, 3.0, delta)
y = np.arange(-2.0, 2.0, delta)
X, Y = np.meshgrid(x, y)
Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
Z = (Z1 - Z2) * 10

plt.contourf(X, Y, Z)

text1=plt.text(0, 0, 'ghghg',color='black',fontsize=14) 
plt.text(1, 1, 'Calculation ',color='black',fontsize=14)
plt.title('Average ')

plt.xlabel('Longtitude ', fontsize=14, color='black')
plt.ylabel('Latitude ', fontsize=14, color='black')
plt.grid(True)

def onselect(eclick, erelease):
     'eclick and erelease are matplotlib events at press and release'
     text1.set_text('Geo ')
     text1.set_x(eclick.xdata)
     text1.set_y(eclick.ydata)
     plt.draw()

def toggle_selector(event):
    print ' Key pressed.'
    if event.key in ['Q', 'q'] and toggle_selector.RS.active:
       print ' RectangleSelector deactivated.'
       toggle_selector.RS.set_active(False)
    if event.key in ['A', 'a'] and not toggle_selector.RS.active:
       print ' RectangleSelector activated.'
       toggle_selector.RS.set_active(True)

def movetext(self):
     print 'clearing plot'
     text1.set_x(np.random.random(1))
     text1.set_y(np.random.random(1))
     plt.draw()


toggle_selector.RS = RectangleSelector(ax, onselect, drawtype='line')
plt.connect('key_press_event', toggle_selector)

buttonaxe = plt.axes([0.7, 0.05, 0.1, 0.1])
bbutton = Button(buttonaxe, 'movetext',color='0.85', hovercolor='0.95')
bbutton.on_clicked(movetext)

plt.show()

放在底部的按钮工作正常。但是在下面的示例中，如果我只是将所有代码放在一个名为 Plotter 的函数中，该按钮会显示在绘图中，但它不起作用。当鼠标悬停在按钮上方时没有变化，并且连接的函数 movetext 没有执行。

from pylab import *
from matplotlib.widgets import  RectangleSelector
from matplotlib.widgets import Button
import numpy as np
import matplotlib.pylab as plt

fig = plt.figure()
ax = fig.add_subplot(111)


def Plotter():

    delta = 0.025
    x = np.arange(-3.0, 3.0, delta)
    y = np.arange(-2.0, 2.0, delta)
    X, Y = np.meshgrid(x, y)
    Z1 = bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
    Z2 = bivariate_normal(X, Y, 1.5, 0.5, 1, 1)
    Z = (Z1 - Z2) * 10
    #Z1 = mlab.bivariate_normal(X, Y, 1.0, 1.0, 0.0, 0.0)
    plt.contourf(X, Y, Z)
    text1=plt.text(0, 0, 'ghghg',color='black',fontsize=14) 
    plt.text(1, 1, 'Calculation ',color='black',fontsize=14)
    plt.title('Average ')

    plt.xlabel('Longtitude ', fontsize=14, color='black')
    plt.ylabel('Latitude ', fontsize=14, color='black')
    plt.grid(True)

    def onselect(eclick, erelease):
         'eclick and erelease are matplotlib events at press and release'
         text1.set_text('Geo ')
         text1.set_x(eclick.xdata)
         text1.set_y(eclick.ydata)
         plt.draw()

    def toggle_selector(event):
        print ' Key pressed.'
        if event.key in ['Q', 'q'] and toggle_selector.RS.active:
           print ' RectangleSelector deactivated.'
           toggle_selector.RS.set_active(False)
        if event.key in ['A', 'a'] and not toggle_selector.RS.active:
           print ' RectangleSelector activated.'
           toggle_selector.RS.set_active(True)

    def movetext(self):
         print 'clearing plot'
         text1.set_x(np.random.random(1))
         text1.set_y(np.random.random(1))
         plt.draw()


    toggle_selector.RS = RectangleSelector(ax, onselect, drawtype='line')
    plt.connect('key_press_event', toggle_selector)

    buttonaxe = plt.axes([0.7, 0.05, 0.1, 0.1])
    bbutton = Button(buttonaxe, 'movetext',color='0.85', hovercolor='0.95')
    bbutton.on_clicked(movetext)
Plotter()    
plt.show()

有人可以解释这种行为吗？我究竟做错了什么？

Answer 1

这是因为bbutton是本地名称，当Plotter()调用结束后，名称bbutton就没有了，什么都没有对 Button 对象的引用，它将被垃圾收集器回收。

要解决这个问题，您可以创建一个对它的虚拟引用，例如将以下行添加到 Plotter 的末尾:

buttonaxe._button = bbutton