在tabWidget内的pyqt5中使用matplotlib绘制另一个图形之前不清除图形

Question

I am learning pyqt 5 and python and wanted to make a simple application that would show a layout with tabs a webpage and a matplotlib graph. When I change a combobox I wanted to show the shape file for a country in the matplotlib graph, however, I can only show the first shapefile. `Below is the code simplified that shows the layout and problem, rather than the shapefile for an example I just have some slightly different functions that should change when the combobox is changed. However, only the very first graph is shown, and although the variables are passed from the combobox, the new function is not plotted. Basically, at this point, all I want to do is to be able to pull the combobox down select the other country and see the new graph appear. Other suggestions are also appreciated. The code sample below.

import numpy as np
import sys
from PyQt5.QtCore import QUrl,QRect,QSize
from PyQt5.QtWebEngineWidgets import QWebEngineSettings, QWebEngineView, QWebEnginePage 
from PyQt5.QtWidgets import (QApplication, QMainWindow,QMenu,QHBoxLayout,QVBoxLayout,QFrame,QLabel,
QSizePolicy, QMessageBox, QWidget, QPushButton,QRadioButton,
QTextBrowser,QDialog,QGroupBox,QTabWidget,QComboBox,QListWidget)

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import shapefile as shp
import matplotlib.pyplot as plt

import random

data_square=[(0,0),(1,0),(1,1),(0,1),(0,0),(1,1)]
data_rectangle=[(0,0),(2,0),(2,1),(0,1),(0,0),(1,1)]

class MyBrowser(QWebEnginePage):

    def userAgentForUrl(self, url):
        return "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36"

class Web(QWebEngineView):

    def load(self, url):
        self.setUrl(QUrl(url))

    def adjustTitle(self):
        self.setWindowTitle(self.title())

    def disableJS(self):
        settings = QWebEngineSettings.globalSettings()
        settings.setAttribute(QWebEngineSettings.JavascriptEnabled, False)




class App(QDialog):
    def __init__(self):
        super().__init__()
        self.title= 'Test Building PyQT5 with Tabs'
        self.left = 40
        self.top = 40
        self.width = 400
        self.height = 100
        self.initUI()


    def initUI(self):        
        #self.setWindowTitle(self.title)
        #self.setGeometry(100,100,1000,800)
        #self.create_my_layout()
        #my_main_window_layout=QVBoxLayout()
        #self.setLayout(my_main_window_layout)
        #self.show()

        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.create_my_layout()

        windowLayout = QVBoxLayout()
        #windowLayout.addWidget(self.horizontalGroupBox)
        self.setLayout(windowLayout)

        self.show()

    def my_combo_active(self,index):
        my_specific_country = self.my_combo.itemText(index)
        if my_specific_country=='Afghanistan':
            m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='abc',sf=data_square)
            print('A')
        if my_specific_country=='Bangladesh':
            m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='def',sf=data_rectangle)
            print('B')


    def create_my_layout(self):
# Set up group boxes along left side of window
        my_groupbox1=QGroupBox('box 1')
        my_groupbox2=QGroupBox('box 2')

        my_button1=QRadioButton('a button')
        my_button1.setChecked(True)
        #radiobutton.toggled.connect(self.on_radio_button_toggled)
        my_button2=QRadioButton('another button')

        my_button5=QRadioButton('more button')
        my_button5.setChecked(True)
        my_button6=QRadioButton('even more button')

        v_box0=QVBoxLayout()
        v_box0.addWidget(my_button1)
        v_box0.addWidget(my_button2)
        my_groupbox1.setLayout(v_box0)

        v_box00=QVBoxLayout()
        v_box00.addWidget(my_button5)
        v_box00.addWidget(my_button6)
        my_groupbox2.setLayout(v_box00)



#set up Tab Widget to end up on right side   
        my_tabWidget=QTabWidget()
        tab1=QWidget()
        tab2=QWidget()

        my_tabWidget.addTab(tab1,"Tab 1")
        my_tabWidget.addTab(tab2,"Tab 2")



# Add To Tab 1
        my_label_country=QLabel('Country')
        my_label_country.setMaximumSize(QSize(1000,50))
        my_label_map=QLabel('Map')

        self.my_combo=QComboBox()
        self.my_combo.activated.connect(self.my_combo_active)
        self.my_graphic=QFrame()
        self.my_graphic.setMinimumSize(QSize(500,500))

        my_list1=QListWidget()
        my_list2=QListWidget()
        my_list3=QListWidget()
        my_button_complete=QPushButton('')
        #my_list4=QListWidget()

        tab1.v_box1=QVBoxLayout()
        tab1.v_box1.addWidget(self.my_combo)
        tab1.v_box1.addWidget(my_label_map)
        tab1.v_box1.addWidget(self.my_graphic)
        tab1.v_box1.addWidget(my_list1)

        tab1.v_box2=QVBoxLayout()
        tab1.v_box2.addWidget(my_list2)

        tab1.v_box3=QVBoxLayout()
        tab1.v_box3.addWidget(my_list3)
        tab1.v_box3.addWidget(my_button_complete)

        tab1.h_box1=QHBoxLayout()
        tab1.h_box1.addLayout(tab1.v_box1)
        tab1.h_box1.addLayout(tab1.v_box2)
        tab1.h_box1.addLayout(tab1.v_box3)

        tab1.setLayout(tab1.h_box1)

# now add Elements to Tab 2 
        my_label_webpage=QLabel('A Web Page')
        my_label_webpage.setMaximumSize(QSize(1000,20))


        #my_combo=QComboBox()
# PC version
        #my_webpage=QWebView()
#Mac version
        my_webpage=Web()
        my_list_exText=QListWidget()



        tab2.v_box1=QVBoxLayout() 
        tab2.v_box1.addWidget(my_webpage)

        tab2.v_box2=QVBoxLayout()
        tab2.v_box2.addWidget(my_list_exText)

        tab2.h_box1=QHBoxLayout()
        tab2.h_box1.addLayout(tab2.v_box1)
        tab2.setLayout(tab2.h_box1)

        my_webpage.load(QUrl("https://google.com"))
        my_webpage.show()


# arrange Group Boxes vertically and Tab on the Right        
        v_box1=QVBoxLayout()
        v_box1.addWidget(my_groupbox1)
        v_box1.addWidget(my_groupbox2)
        v_box2=QVBoxLayout()
        v_box2.addWidget(my_tabWidget)
        h_box1=QHBoxLayout()
        h_box1.addLayout(v_box1)
        h_box1.addLayout(v_box2)   
        self.setLayout(h_box1)

        m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='xyz',sf=data_square)

# Fill the ComboBox of Countries
        my_sample_countries= ['Afghanistan','Bangladesh']
        for country in my_sample_countries:
            self.my_combo.addItem(country)

class PlotCanvas(FigureCanvas):

    def __init__(self, parent=None, width=5, height=4, dpi=100,atest='xyz',sf=data_square):



        fig = Figure(figsize=(width, height), dpi=dpi)

        axes = fig.add_subplot(111)
        axes.hold(False)

        FigureCanvas.__init__(self, fig)

        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
                QSizePolicy.Expanding,
                QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

        ax = self.figure.add_subplot(111)


        x = np.linspace(0, 3 * np.pi, 400)
        y = np.sin(x ** 3) 

        print('atest',atest)

        if atest=='abc':
            x = np.linspace(0, 2 * np.pi, 400)
            y = np.sin(x ** 2)
            print('A case')
        if atest=='def':
            x = np.linspace(0, 4 * np.pi, 400)
            y = np.sin(x ** 4)
            print('B case')

        ax.plot(x,y)        

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())

Answer 1

have to manually force a figure draw

ax.figure.canvas.draw()
self.show()

Try it:

import numpy as np
import sys
from PyQt5.QtCore import QUrl,QRect,QSize
from PyQt5.QtWebEngineWidgets import QWebEngineSettings, QWebEngineView, QWebEnginePage 
from PyQt5.QtWidgets import (QApplication, QMainWindow,QMenu,QHBoxLayout,QVBoxLayout,QFrame,QLabel,
        QSizePolicy, QMessageBox, QWidget, QPushButton,QRadioButton,
        QTextBrowser,QDialog,QGroupBox,QTabWidget,QComboBox,QListWidget)

from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure
import shapefile as shp
import matplotlib.pyplot as plt

import random

data_square=[(0,0),(1,0),(1,1),(0,1),(0,0),(1,1)]
data_rectangle=[(0,0),(2,0),(2,1),(0,1),(0,0),(1,1)]

class MyBrowser(QWebEnginePage):

    def userAgentForUrl(self, url):
        return "Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/41.0.2228.0 Safari/537.36"

class Web(QWebEngineView):

    def load(self, url):
        self.setUrl(QUrl(url))

    def adjustTitle(self):
        self.setWindowTitle(self.title())

    def disableJS(self):
        settings = QWebEngineSettings.globalSettings()
        settings.setAttribute(QWebEngineSettings.JavascriptEnabled, False)




class App(QDialog):
    def __init__(self):
        super().__init__()
        self.title= 'Test Building PyQT5 with Tabs'
        self.left   =  40
        self.top    =  40
        self.width  = 400
        self.height = 100
        self.initUI()


    def initUI(self):        
        #self.setWindowTitle(self.title)
        #self.setGeometry(100,100,1000,800)
        #self.create_my_layout()
        #my_main_window_layout=QVBoxLayout()
        #self.setLayout(my_main_window_layout)
        #self.show()

        self.setWindowTitle(self.title)
        self.setGeometry(self.left, self.top, self.width, self.height)

        self.create_my_layout()

        windowLayout = QVBoxLayout()
        #windowLayout.addWidget(self.horizontalGroupBox)
        self.setLayout(windowLayout)

        self.show()

    def my_combo_active(self,index):
        my_specific_country = self.my_combo.itemText(index)
        if my_specific_country == 'Afghanistan':
            m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='abc',sf=data_square)
            print('A')
        if my_specific_country == 'Bangladesh':
            m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='def',sf=data_rectangle)
            print('B')


    def create_my_layout(self):
# Set up group boxes along left side of window
        my_groupbox1=QGroupBox('box 1')
        my_groupbox2=QGroupBox('box 2')

        my_button1=QRadioButton('a button')
        my_button1.setChecked(True)
        #radiobutton.toggled.connect(self.on_radio_button_toggled)
        my_button2=QRadioButton('another button')

        my_button5=QRadioButton('more button')
        my_button5.setChecked(True)
        my_button6=QRadioButton('even more button')

        v_box0=QVBoxLayout()
        v_box0.addWidget(my_button1)
        v_box0.addWidget(my_button2)
        my_groupbox1.setLayout(v_box0)

        v_box00=QVBoxLayout()
        v_box00.addWidget(my_button5)
        v_box00.addWidget(my_button6)
        my_groupbox2.setLayout(v_box00)



#set up Tab Widget to end up on right side   
        my_tabWidget=QTabWidget()
        tab1=QWidget()
        tab2=QWidget()

        my_tabWidget.addTab(tab1,"Tab 1")
        my_tabWidget.addTab(tab2,"Tab 2")



# Add To Tab 1
        my_label_country = QLabel('Country')
        my_label_country.setMaximumSize(QSize(1000,50))
        my_label_map = QLabel('Map')

        self.my_combo = QComboBox()
        self.my_combo.activated.connect(self.my_combo_active)
        self.my_graphic=QFrame()
        self.my_graphic.setMinimumSize(QSize(500,500))

        my_list1 = QListWidget()
        my_list2 = QListWidget()
        my_list3 = QListWidget()
        my_button_complete=QPushButton('')
        #my_list4=QListWidget()

        tab1.v_box1 = QVBoxLayout()
        tab1.v_box1.addWidget(self.my_combo)
        tab1.v_box1.addWidget(my_label_map)
        tab1.v_box1.addWidget(self.my_graphic)
        tab1.v_box1.addWidget(my_list1)

        tab1.v_box2 = QVBoxLayout()
        tab1.v_box2.addWidget(my_list2)

        tab1.v_box3 = QVBoxLayout()
        tab1.v_box3.addWidget(my_list3)
        tab1.v_box3.addWidget(my_button_complete)

        tab1.h_box1 = QHBoxLayout()
        tab1.h_box1.addLayout(tab1.v_box1)
        tab1.h_box1.addLayout(tab1.v_box2)
        tab1.h_box1.addLayout(tab1.v_box3)

        tab1.setLayout(tab1.h_box1)

# now add Elements to Tab 2 
        my_label_webpage=QLabel('A Web Page')
        my_label_webpage.setMaximumSize(QSize(1000,20))


        #my_combo=QComboBox()
# PC version
        #my_webpage=QWebView()
#Mac version
        my_webpage=Web()
        my_list_exText=QListWidget()



        tab2.v_box1=QVBoxLayout() 
        tab2.v_box1.addWidget(my_webpage)

        tab2.v_box2=QVBoxLayout()
        tab2.v_box2.addWidget(my_list_exText)

        tab2.h_box1=QHBoxLayout()
        tab2.h_box1.addLayout(tab2.v_box1)
        tab2.setLayout(tab2.h_box1)

        my_webpage.load(QUrl("https://google.com"))
        my_webpage.show()


# arrange Group Boxes vertically and Tab on the Right        
        v_box1=QVBoxLayout()
        v_box1.addWidget(my_groupbox1)
        v_box1.addWidget(my_groupbox2)
        v_box2=QVBoxLayout()
        v_box2.addWidget(my_tabWidget)
        h_box1=QHBoxLayout()
        h_box1.addLayout(v_box1)
        h_box1.addLayout(v_box2)   
        self.setLayout(h_box1)

        #m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='xyz',sf=data_square)
        m = PlotCanvas(self.my_graphic, width=5, height=5, dpi=100,atest='xyz',sf=data_square)

# Fill the ComboBox of Countries
        my_sample_countries= ['Afghanistan','Bangladesh']
        for country in my_sample_countries:
            self.my_combo.addItem(country)

class PlotCanvas(FigureCanvas):

    def __init__(self, parent=None, width=5, height=4, dpi=100, atest='xyz', sf=data_square):

        fig = Figure(figsize=(width, height), dpi=dpi)

        axes = fig.add_subplot(111)
        axes.hold(False)

        FigureCanvas.__init__(self, fig)

        self.setParent(parent)

        FigureCanvas.setSizePolicy(self,
                QSizePolicy.Expanding,
                QSizePolicy.Expanding)
        FigureCanvas.updateGeometry(self)

        ax = self.figure.add_subplot(111)


        x = np.linspace(0, 3 * np.pi, 400)
        y = np.sin(x ** 3) 

        print('atest', atest)

        if atest == 'abc':
            x = np.linspace(0, 2 * np.pi, 400)
            y = np.sin(x ** 2)
            print('A case')
        if atest == 'def':
            x = np.linspace(0, 4 * np.pi, 400)
            y = np.sin(x ** 4)
            print('B case')

        ax.plot(x,y)      
        # have to manually force a figure draw
        ax.figure.canvas.draw()     # +  
        self.show()                 # +       

if __name__ == '__main__':
    app = QApplication(sys.argv)
    ex = App()
    sys.exit(app.exec_())