使用 Qt4 进行 Python 分散更新 - Qslider

Question

我正在尝试使用 PyQt4 在 Python3 中编写 GUI。

对于数据可视化，我需要隔离由函数 Whole_plot() 绘制的曲线上的特定点。为此，我目前正在使用一个 slider ，让 GUI 用户选择一个兴趣点。当 slider_value 更改时，通过调用函数 point_plot() 选择并绘制该点。

关于之前的一些答案，我现在尝试通过 matplotlib.animation 更新我的图表(参见 post python matplotlib update scatterplot from a function)。但由于某些原因，我仍然得到了错误的更新，有人可以帮我找出我的代码中的问题是什么吗？

import sys
import numpy as np
from PyQt4 import QtGui
from PyQt4 import QtCore
import matplotlib.pyplot as plt
import matplotlib.animation
#
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
#%%
# some Arbitrary data
nbr_points = 500
my_X_data = np.linspace(-10,10,nbr_points)
my_Y_data = my_X_data**3 + 100*np.cos(my_X_data*5)

class MyWidget(QtGui.QWidget):

    def __init__(self):
        super(MyWidget, self).__init__()
        self.initUI()

    def initUI(self):

        self.setGeometry(600,300,1000,600)

        grid = QtGui.QGridLayout()
        self.setLayout(grid)

        self.figure_1 = plt.figure(figsize=(15,5))
        self.canvas_1 = FigureCanvas(self.figure_1)

        self.toolbar = NavigationToolbar(self.canvas_1, self)
        grid.addWidget(self.canvas_1, 2,0,1,2)
        grid.addWidget(self.toolbar, 0,0,1,2)


        # Slider
        self.slider = QtGui.QSlider(QtCore.Qt.Horizontal)
        self.slider.setMinimum(0) 
        self.slider.setMaximum(nbr_points-1) 
        self.slider.setTickInterval(1)
        self.slider.valueChanged.connect(self.point_plot)

        # Slider info box
        self.label = QtGui.QLabel(self)
        grid.addWidget(self.label,4,0)

        #  +1 / -1 buttons
        btn_plus_one = QtGui.QPushButton('+1', self)
        btn_plus_one.clicked.connect(self.value_plus_one)
        btn_minus_one = QtGui.QPushButton('-1', self)
        btn_minus_one.clicked.connect(self.value_minus_one)       

        hbox = QtGui.QHBoxLayout()
        hbox.addWidget(btn_minus_one)
        hbox.addWidget(self.slider)
        hbox.addWidget(btn_plus_one)
        grid.addLayout(hbox, 3,0,1,3)


        self.whole_plot()
        self.point_plot()
        self.show()



    def whole_plot(self):
        ax1 = self.figure_1.add_subplot(111)
        ax1.clear()
        ax1.cla()
        #
        ax1.plot(my_X_data,my_Y_data,'b-')        
        #
        ax1.set_xlim([-10,10])  
        ax1.set_ylim([-1000,1000])  
        ax1.set_xlabel('X')             
        ax1.set_ylabel('Y')  
        #
        self.canvas_1.draw()


    def point_plot(self):      

        ax1 = self.figure_1.add_subplot(111)       
        #     
        X_point, Y_point = [],[]
        scat = ax1.scatter(X_point,Y_point, s=100,c='k')

        def animate(i):
            index_slider_value = self.slider.value()
            X_point = my_X_data[index_slider_value,]
            Y_point = my_Y_data[index_slider_value,]
            scat.set_offsets(np.c_[X_point,Y_point])  

        anim = matplotlib.animation.FuncAnimation(self.figure_1,animate, frames=my_X_data, interval=200, repeat=True) 
        self.canvas_1.draw()


    def value_plus_one(self):
        # slider +1
        if self.slider.value() < (my_X_data.shape[0]-1): 
            index_slider_value = self.slider.value() + 1
            self.slider.setValue(index_slider_value)


    def value_minus_one(self):
        # slider -1
        if self.slider.value() > 0:
            index_slider_value = self.slider.value() - 1
            self.slider.setValue(index_slider_value)



def main():
    app = QtGui.QApplication(sys.argv)
    MyWidget()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

Answer 1

您必须了解什么是重用比创建更好，在这种情况下，您只需创建一个scatter并在值达到时使用set_offsets()更新数据 slider 的变化，因此不需要 FuncAnimation。

import numpy as np
from PyQt4 import QtCore, QtGui
import matplotlib.pyplot as plt
import matplotlib.animation
#
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar
#%%
# some Arbitrary data
nbr_points = 500
my_X_data = np.linspace(-10,10,nbr_points)
my_Y_data = my_X_data**3 + 100*np.cos(my_X_data*5)

class MyWidget(QtGui.QWidget):
    def __init__(self):
        super(MyWidget, self).__init__()
        self.initUI()

    def initUI(self):
        self.setGeometry(600,300,1000,600)
        self.figure_1 = plt.figure(figsize=(15,5))
        self.canvas = FigureCanvas(self.figure_1)
        self.toolbar = NavigationToolbar(self.canvas, self)
        # Slider
        self.slider = QtGui.QSlider(minimum=0, 
            maximum= nbr_points-1, 
            orientation=QtCore.Qt.Horizontal,
            tickInterval=1)
        self.slider.valueChanged.connect(self.on_valueChanged)
        # Slider info box
        self.label = QtGui.QLabel()
        #  +1 / -1 buttons
        btn_plus_one = QtGui.QPushButton('+1')
        btn_plus_one.clicked.connect(self.value_plus_one)
        btn_minus_one = QtGui.QPushButton('-1')
        btn_minus_one.clicked.connect(self.value_minus_one)       

        grid = QtGui.QGridLayout(self)
        grid.addWidget(self.canvas, 2, 0, 1, 2)
        grid.addWidget(self.toolbar, 0, 0, 1, 2)
        grid.addWidget(self.label, 4, 0)
        hbox = QtGui.QHBoxLayout()
        hbox.addWidget(btn_minus_one)
        hbox.addWidget(self.slider)
        hbox.addWidget(btn_plus_one)
        grid.addLayout(hbox, 3, 0, 1, 3)
        self.whole_plot()

    def whole_plot(self):
        ax = self.figure_1.add_subplot(111)
        ax.clear()
        ax.plot(my_X_data,my_Y_data,'b-')        
        ax.set_xlim([-10,10])  
        ax.set_ylim([-1000,1000])  
        ax.set_xlabel('X')             
        ax.set_ylabel('Y')  
        self.canvas.draw()
        X_point, Y_point = [],[]
        self.scat = ax.scatter(X_point, Y_point, s=100,c='k')
        # set initial
        self.on_valueChanged(self.slider.value())

    @QtCore.pyqtSlot(int)
    def on_valueChanged(self, value):
        X_point = my_X_data[value,]
        Y_point = my_Y_data[value,]
        self.scat.set_offsets(np.c_[X_point,Y_point])   
        self.canvas.draw()

    @QtCore.pyqtSlot()
    def value_plus_one(self):
        self.slider.setValue(self.slider.value() + 1)

    @QtCore.pyqtSlot()
    def value_minus_one(self):
        self.slider.setValue(self.slider.value() - 1)

def main():
    import sys
    app = QtGui.QApplication(sys.argv)
    w = MyWidget()
    w.show()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

另一方面，如果QSlider小于最小值或大于最大值，则不会更新该值