Hi,
I spend some time writing up the question below on Stackoverflow which
immediately was closed as a duplicate of other posts. To my best
knowledge, these posts did not answer my questions - so I'll try my luck
here instead:
I am using the qt backengine for setting up a QWidget that embeds a
matplotlib scene. When the widget is closed it appears that many of the
matplotlib objects that were part of the plot still are alive in Python
space.
My question is basically the following: What actions should I take to
clean up the figure and axes objects etc. that were part of the plot
widget? The qt backend comes with a figure manager, but it appears a
little unclear how it should be used.
I have attached a small unit test example that sets up a plot. When the
plot appears, just close it, and the test will garbage collects the
plot, and then display info of the matplotlib objects that are still
alive in Python space. Clearly both the path of the plot, and several
Bbox objects are still referenced.
Our current unit test suite contains almost 10000 GUI tests and its
imperative that proper object space clean up is done after each test.
Any help is much appreciated.
Best regards,
Mads
--
+-----------------------------------------------------+
| Mads Ipsen |
+----------------------+------------------------------+
| Gåsebæksvej 7, 4. tv | |
| DK-2500 Valby | phone: +45-29716388 |
| Denmark | email: [email protected] |
+----------------------+------------------------------+
import sys
import gc
import numpy
import unittest
from PyQt4 import QtCore, QtGui
from matplotlib.figure import Figure
from matplotlib.backends.backend_qt4agg import FigureCanvasQTAgg
# Need a Qt app to handle events
QT_APP = QtGui.QApplication(sys.argv)
class Plot2D(QtGui.QWidget):
"""
2D Plot class based on a matplotlib canvas.
"""
def __init__(self, parent=None, testing=False):
"""
Constructor.
@param parent : Parent widget.
@param testing : Set to True if testing
"""
# Initialize base class
QtGui.QWidget.__init__(self, parent)
# Set a layout
layout = QtGui.QVBoxLayout()
self.setLayout(layout)
# Set up figure
self._figure = Figure()
self._canvas = FigureCanvasQTAgg(self._figure)
# Add widgets to the layout
layout.addWidget(self._canvas)
# Draw something
self._axes = self._figure.add_subplot(111)
self.draw()
def draw(self):
"""
Redraws a figure. Added for unit testing purposes but may also be used for
inspiration on how to make a plot.
"""
str = '1 2 3 4'
data = map(int, str.split())
x = range(len(data))
# clear the axes and redraw the plot anew
self._axes.clear()
self._axes.bar(
left=x,
height=data,
width=8.0/ 100.0,
align='center',
alpha=0.44,
picker=5)
t = numpy.arange(0.0, 3.0, 0.01)
s = numpy.sin(2*numpy.pi*t)
self._axes.plot(t, s, picker=5)
self._axes.set_title('This is a title')
self._axes.set_xlabel('Clock is ticking')
self._axes.set_ylabel('Time is running')
self._canvas.draw()
class Plot2DTest(unittest.TestCase):
def setUp(self):
self._plot = Plot2D()
def tearDown(self):
self._plot.close()
del self._plot
gc.collect()
@classmethod
def tearDownClass(cls):
QtGui.qApp.processEvents()
print
print 'Performing tear down for', cls
print 'Active matplotlib objects\n--------------:'
objs = [o for o in gc.get_objects() if 'matplotlib' in str(type(o))]
for o in objs:
print o
def testConstruction(self):
""" Test that class instantiation suceeds """
self._plot.show()
QtGui.qApp.exec_()
if __name__ == '__main__':
unittest.main()
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