How to insert matplotlib in pyqt - for dummies

Question

I'm currently trying to embed a graph that I want to build in the pyqt4 user interface that I developed. Since I am almost completely new to programming, I don’t understand how people invested in the examples I found - this one (below) and this one .

It would be great if someone could post a step-by-step explanation, or at least a very small, very simple code that creates, for example, a graph and a button in the same pyqt4 GUI.

Answer 1

This is actually not so difficult. The corresponding Qt widgets are in matplotlib.backends.backend_qt4agg . FigureCanvasQTAgg and NavigationToolbar2QT are usually what you need. These are regular Qt widgets. You treat them like any other widget. Below is a very simple example with Figure , Navigation and a single button that draws some random data. I added comments to explain.

 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• Replace outdated ax.hold(False) with ax.clear()

Answer 2

The following is an adaptation of the previous code for use in PyQt5 and Matplotlib 2.0 . There are a number of small changes: the structure of the PyQt submodules, another submodule from matplotlib, the 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_())