Article Outline
Python matplotlib example 'matplotlibqt5base'
Functions in program:
def main():
Modules used in program:
import matplotlib.pyplot as plt
import numpy as np
import sys
python matplotlibqt5base
Python matplotlib example: matplotlibqt5base
import sys
import numpy as np
import matplotlib.pyplot as plt
# import relevant classes from PyQt
from PyQt5.QtWidgets import QApplication, QMainWindow, QPushButton, QWidget, QLabel
from PyQt5.QtWidgets import QHBoxLayout, QVBoxLayout, QSizePolicy
from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas
class MyMainWindow(QMainWindow):
''' the main window potentially with menus, statusbar, ... '''
def __init__(self):
super().__init__()
self.resize(600, 300)
self.move(300, 200)
central_widget = MyCentralWidget(self)
self.setCentralWidget(central_widget)
self.setWindowTitle('PyQt MainWindow with matplotlib figure')
self.statusBar().showMessage('Waiting for a button to be pressed')
class MyCentralWidget(QWidget):
''' everything in the main area of the main window '''
def __init__(self, main_window):
super().__init__()
self.main_window = main_window
# define left button
left_button = QPushButton('Plot x^2', self)
left_button.clicked.connect(self.on_left_button_clicked) # <-- registers which function to call when the button is clicked
# define right button
right_button = QPushButton('Plot x^3', self)
right_button.clicked.connect(self.on_right_button_clicked)
# define figure canvas
self.mpl_widget = MyMplWidget() # <-- create the matplotlib figure widget (class defined below)
# place the buttons into a horizontal box layout
hbox = QHBoxLayout()
hbox.addStretch(1) # <-- add an expanding box
hbox.addWidget(left_button) # <-- add the left button
hbox.addWidget(right_button) # <-- add the right button
# place this box and the label into a vertical box layout
vbox = QVBoxLayout()
vbox.addWidget(self.mpl_widget) # <-- add the figure
vbox.addLayout(hbox) # <-- add the hbox with the buttons
#use the box layout to fill the window
self.setLayout(vbox)
def on_left_button_clicked(self):
''' event handler for click on left button '''
self.main_window.statusBar().showMessage('Plot of x^2')
self.mpl_widget.plot_power(2)
def on_right_button_clicked(self):
''' event handler for click on right button '''
self.main_window.statusBar().showMessage('Plot of x^3')
self.mpl_widget.plot_power(3)
class MyMplWidget(FigureCanvas):
''' both a QWidget and a matplotlib figure '''
def __init__(self, parent=None, figsize=(4, 3), dpi=100):
self.fig = plt.figure(figsize=figsize, dpi=dpi) # creates a matplotlib figure
FigureCanvas.__init__(self, self.fig) # initialises the FigureCanvas object with the figure
self.setParent(parent)
# ensure figure expands with window
FigureCanvas.setSizePolicy(self, QSizePolicy.Expanding, QSizePolicy.Expanding)
FigureCanvas.updateGeometry(self)
def plot_power(self, n):
''' clear the figure and plot x**n for -1 < x < 1 '''
self.fig.clf() # <-- clears the figure
self.ax = self.fig.add_subplot(1, 1, 1)
x = np.linspace(-1, 1, 101)
self.ax.plot(x, x**n, 'b')
self.draw()
app = None
def main():
global app
app = QApplication(sys.argv)
w = MyMainWindow()
w.show()
app.exec()
if __name__ == '__main__':
main()
Python links
- Learn Python: https://pythonbasics.org/
- Python Tutorial: https://pythonprogramminglanguage.com