matplotlib onPick事件注册两次

Question

作为一个更大的项目的一部分，我正在更新Pyqt5中嵌入的matplotlib上的图形。我有一个onpick事件，它将注释添加到散点并将其删除。在以类似于下面的方式更新我的绘图后，onPick功能会注册两次。有一些潜在的问题没有被正确删除。除了这个数字之外，我还想知道我可以清楚哪些可以纠正我的问题。

简单的例子突出问题：

import sys 

from PyQt5.QtGui import * 
from PyQt5.QtWidgets import * 
from PyQt5.QtCore import * 

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas 
from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar 
from mpl_toolkits.mplot3d import Axes3D 
import matplotlib.pyplot as plt 

class plot(QWidget): 
    def __init__(self): 
     super().__init__() 
    self.figure = plt.figure() 
    self.canvas = FigureCanvas(self.figure) 

    self.Layout = QVBoxLayout() 

    self.xarray = [1,2,3,4,5,6] 
    self.yarray = [6,7,5,4,2,1] 

    update_btn = QPushButton("Update Plot", self) 
    self.Layout.addWidget(update_btn, 1) 
    update_btn.clicked.connect(self.updateplot) 

    self.createplot() 

    self.setLayout(self.Layout) 

def updateplot(self): 

    self.xarray = [6,7,5,3,2,1] 
    self.figure.clear() 
    self.createplot() 

def createplot(self): 

    ax = self.figure.add_subplot(1,1,1) 
    ax.grid() 
    val = self.displayval(ax) 
    self.plot = ax.plot(self.xarray, self.yarray,'o', marker = 'o', c= 'b', picker = 5)[0] 

    self.Layout.addWidget(self.canvas, 2) 
    self.canvas.draw() 

def displayval(self, ax): 
    def onPick(event): 
     print("connecting") 
     plot = event.artist 

     xval = plot.get_xdata() 
     yval = plot.get_ydata() 
     ind = event.ind 

     if xval[ind].size > 1 or yval[ind].size > 1: return 

     xy = (xval[ind][0], yval[ind][0]) 

     ann = ax.annotate('(%f , %f)' % xy, xy= xy) 

     self.figure.canvas.draw() 

    self.figure.canvas.mpl_connect('pick_event', onPick) 
    return onPick 

if __name__ == '__main__': 
    appl = QApplication(sys.argv) 
    main = plot() 
    main.show() 
    sys.exit(appl.exec_()) 

注：我曾尝试更新的东西轴线值一样

ax.set_xaxis() 

然而，这并不正确地呈现在我的程序中的数据，因此一备选答案将是首选。

Answer 1

下面是解决问题的方法。感谢@ImportanceOfBeingErnest解释问题发生的原因。从那里我能够解决这个问题。一旦更新，点击注释只出现一次。该解决方案仅调用displayval一次，并将ax更改为'self.ax'并更新对象变量。

import sys 

from PyQt5.QtGui import * 
from PyQt5.QtWidgets import * 
from PyQt5.QtCore import * 

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas 
from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar 
from mpl_toolkits.mplot3d import Axes3D 
import matplotlib.pyplot as plt 

class plot(QWidget): 
    def __init__(self): 
     super().__init__() 

     self.figure = plt.figure() 
     self.canvas = FigureCanvas(self.figure) 

     self.Layout = QVBoxLayout() 

     self.xarray = [1,2,3,4,5,6] 
     self.yarray = [6,7,5,4,2,1] 
     self.init_trigger = True 

     update_btn = QPushButton("Update Plot", self) 
     self.Layout.addWidget(update_btn, 1) 
     update_btn.clicked.connect(self.updateplot) 

     self.createplot() 

     self.setLayout(self.Layout) 

    def updateplot(self): 

     self.xarray = [6,7,5,3,2,1] 
     self.figure.clear() 
     self.createplot() 

    def createplot(self): 


     self.ax = self.figure.add_subplot(1,1,1) 
     self.ax.grid() 
     if self.init_trigger: val = self.displayval() 
     self.plot = self.ax.plot(self.xarray, self.yarray,'o', marker = 'o', c= 'b', picker = 5)[0] 

     self.Layout.addWidget(self.canvas, 2) 
     self.canvas.draw() 
     self.init_trigger = False 

    def displayval(self): 
     def onPick(event): 
      print("connecting") 
      plot = event.artist 

      xval = plot.get_xdata() 
      yval = plot.get_ydata() 
      ind = event.ind 

      if xval[ind].size > 1 or yval[ind].size > 1: return 

      xy = (xval[ind][0], yval[ind][0]) 

      ann = self.ax.annotate('(%f , %f)' % xy, xy= xy) 

      self.figure.canvas.draw() 

     self.figure.canvas.mpl_connect('pick_event', onPick) 
     return onPick 

if __name__ == '__main__': 
    appl = QApplication(sys.argv) 
    main = plot() 
    main.show() 
    sys.exit(appl.exec_())