How to embed matplotlib in pyqt - for Dummies

Question

I am currently trying to embed a graph I want to plot in a pyqt4 user interface I designed. As I am almost completely new to programming - I do not get how people did the embedding in the examples I found - this one (at the bottom) and that one.

It would be awesome if anybody could post a step-by-step explanation or at least a very small, very simple code only creating e.g. a graph and a button in one pyqt4 GUI.

Answer 1

It is not that complicated actually. Relevant Qt widgets are in matplotlib.backends.backend_qt4agg. FigureCanvasQTAgg and NavigationToolbar2QT are usually what you need. These are regular Qt widgets. You treat them as any other widget. Below is a very simple example with a Figure, Navigation and a single button that draws some random data. I've added comments to explain things.

import sys from PyQt4 import QtGui  from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas from matplotlib.backends.backend_qt4agg import NavigationToolbar2QT as NavigationToolbar from matplotlib.figure import Figure  import random  class Window(QtGui.QDialog):     def __init__(self, parent=None):         super(Window, self).__init__(parent)          # a figure instance to plot on         self.figure = Figure()          # this is the Canvas Widget that displays the `figure`         # it takes the `figure` instance as a parameter to __init__         self.canvas = FigureCanvas(self.figure)          # this is the Navigation widget         # it takes the Canvas widget and a parent         self.toolbar = NavigationToolbar(self.canvas, self)          # Just some button connected to `plot` method         self.button = QtGui.QPushButton('Plot')         self.button.clicked.connect(self.plot)          # set the layout         layout = QtGui.QVBoxLayout()         layout.addWidget(self.toolbar)         layout.addWidget(self.canvas)         layout.addWidget(self.button)         self.setLayout(layout)      def plot(self):         ''' plot some random stuff '''         # random data         data = [random.random() for i in range(10)]          # create an axis         ax = self.figure.add_subplot(111)          # discards the old graph         ax.clear()          # plot data         ax.plot(data, '*-')          # refresh canvas         self.canvas.draw()  if __name__ == '__main__':     app = QtGui.QApplication(sys.argv)      main = Window()     main.show()      sys.exit(app.exec_()) 

Edit:

Updated to reflect comments and API changes.

• NavigationToolbar2QTAgg changed with NavigationToolbar2QT
• Directly import Figure instead of pyplot
• Replace deprecated ax.hold(False) with ax.clear()

Answer 2

Below is an adaptation of previous code for using under PyQt5 and Matplotlib 2.0. There are a number of small changes: structure of PyQt submodules, other submodule from matplotlib, deprecated method has been replaced...

 import sys from PyQt5.QtWidgets import QDialog, QApplication, QPushButton, QVBoxLayout  from matplotlib.backends.backend_qt5agg import FigureCanvasQTAgg as FigureCanvas from matplotlib.backends.backend_qt5agg import NavigationToolbar2QT as NavigationToolbar import matplotlib.pyplot as plt  import random  class Window(QDialog):     def __init__(self, parent=None):         super(Window, self).__init__(parent)          # a figure instance to plot on         self.figure = plt.figure()          # this is the Canvas Widget that displays the `figure`         # it takes the `figure` instance as a parameter to __init__         self.canvas = FigureCanvas(self.figure)          # this is the Navigation widget         # it takes the Canvas widget and a parent         self.toolbar = NavigationToolbar(self.canvas, self)          # Just some button connected to `plot` method         self.button = QPushButton('Plot')         self.button.clicked.connect(self.plot)          # set the layout         layout = QVBoxLayout()         layout.addWidget(self.toolbar)         layout.addWidget(self.canvas)         layout.addWidget(self.button)         self.setLayout(layout)      def plot(self):         ''' plot some random stuff '''         # random data         data = [random.random() for i in range(10)]          # instead of ax.hold(False)         self.figure.clear()          # create an axis         ax = self.figure.add_subplot(111)          # discards the old graph         # ax.hold(False) # deprecated, see above          # plot data         ax.plot(data, '*-')          # refresh canvas         self.canvas.draw()  if __name__ == '__main__':     app = QApplication(sys.argv)      main = Window()     main.show()      sys.exit(app.exec_())