PyQt and Matplotlib: creating a copy of a plot

Question

I am new to matplotlib and I have been struggling with implementing a feature for quite some time. Basically I have a plot embedded into a widget and I want to (on button press) create a new Widget with this exact same plot on it. Is there an easy way to do this? [Assuming I already have all the action handlers implemented]

Answer 1

The following is butchered from the embedding_in_qt4 example of matplotlib

import sys
from PyQt4 import QtGui, QtCore

from numpy import arange, sin, pi
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg as FigureCanvas
from matplotlib.figure import Figure


class MyMplCanvas(FigureCanvas):
    """Ultimately, this is a QWidget (as well as a FigureCanvasAgg, etc.)."""
    def __init__(self, parent=None, width=5, height=4, dpi=100):
        fig = Figure(figsize=(width, height), dpi=dpi)
        self.fig = fig
        self.axes = fig.add_subplot(111)
        # We want the axes cleared every time plot() is called
        self.axes.hold(False)

        self.compute_initial_figure()
        FigureCanvas.__init__(self, fig)
        self.setParent(parent)

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

    def compute_initial_figure(self):
        pass


class MyStaticMplCanvas(MyMplCanvas):
    """Simple canvas with a sine plot."""
    def compute_initial_figure(self):
        t = arange(0.0, 3.0, 0.01)
        s = sin(2*pi*t)
        self.axes.plot(t, s)


class ApplicationWindow(QtGui.QWidget):
    def __init__(self):
        QtGui.QWidget.__init__(self)
        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.main_widget = QtGui.QWidget(self)
        l = QtGui.QVBoxLayout(self)
        sc = MyStaticMplCanvas(self, width=5, height=4, dpi=100)
        self.sc = sc
        l.addWidget(sc)
        but = QtGui.QPushButton("make_new", self)
        but.clicked.connect(self.again)
        l.addWidget(but)

    def again(self):
        win = MyMplCanvas()
        win.fig = self.sc.fig
        FigureCanvas.__init__(win, win.fig)
        self.win = win
        win.show()

qApp = QtGui.QApplication(sys.argv)
aw = ApplicationWindow()
aw.show()
sys.exit(qApp.exec_())

Note how the canvas keeps a reference to its figure object and the application keeps a reference to the new canvas.