Python:matplotlib按钮不起作用

Question

我的代码包含一个称为 bbutton的按钮，当按下时执行movetext函数：

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()

放置在底部的按钮正常工作。但是在下面的示例中，如果我只是将所有代码放入一个称为Plotter的函数中，则按钮显示在图中，但它不起作用。当鼠标徘徊在按钮上方而连接的函数movetext时，无需更改。

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()呼叫完成后，名称bbutton已消失，没有任何参考按钮对象，并且将由垃圾收集器回收。

要解决此问题，您可以创建一个虚拟引用，例如将以下行添加到Plotter的末尾：

buttonaxe._button = bbutton