I want to embed a graph in a pyqt4 user interface. I do not understand how people did the embedding in the examples I found - this one (at the bottom) and that one.
Could anyone 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.
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
Figure
instead of pyplot
ax.hold(False)
with ax.clear()