Qrplot crashes on Chrome running under Windows

Course Support ROS Basics In 5 Days (Python)
1

Hi,

I’m on Chapter 5: ROS debugging tools.

I’m unable to run qrtplot, it crashes with this info (any thought about how to solve it?):

user:~$ rqt_plot
/usr/local/lib/python2.7/dist-packages/matplotlib/axis.py:1086: UserWarning: Unable to find pixel distance along axis for interval padding of ticks;assuming no interval padding needed.
  warnings.warn("Unable to find pixel distance along axis "
/usr/local/lib/python2.7/dist-packages/matplotlib/axis.py:1096: UserWarning: Unable to find pixel distance along axis for interval padding of ticks;assuming no interval padding needed.
  warnings.warn("Unable to find pixel distance along axis "
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_plot/data_plot/mat_data_plot.py", line 107, in resizeEvent
    self.figure.tight_layout()
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/figure.py", line 2307, in tight_layout
    pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/tight_layout.py", line 349, in get_tight_layout_figure
    pad=pad, h_pad=h_pad, w_pad=w_pad)
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/tight_layout.py", line 117, in auto_adjust_subplotpars
    fig.transFigure.inverted())
  File "/usr/local/lib/python2.7/dist-packages/matplotlib/transforms.py", line 1901, in inverted
    self._inverted = Affine2D(inv(mtx), shorthand_name=shorthand_name)
  File "/usr/local/lib/python2.7/dist-packages/numpy/linalg/linalg.py", line 551, in inv
    ainv = _umath_linalg.inv(a, signature=signature, extobj=extobj)
  File "/usr/local/lib/python2.7/dist-packages/numpy/linalg/linalg.py", line 97, in _raise_linalgerror_singular
    raise LinAlgError("Singular matrix")
numpy.linalg.LinAlgError: Singular matrix
2

Hi @paedusan,

I apologize for this error.

May I ask that you try again, since these error sometimes popup randomly and I just tried now and could not reproduce the error?

Please let us know so that we can see what might be happening to your specific VM. Thanks in advance.

1 Like
3

Hi @bayodesegun,

I tried again and it still did not work. Now, I’ve got the following error (and the graphical interface goes black):

user:~/catkin_ws/devel$ rqt_plot
QXcbConnection: XCB error: 2 (BadValue), sequence: 438, resource id: 600, major code: 130 (Unknown), minor code: 3
QXcbConnection: XCB error: 2 (BadValue), sequence: 439, resource id: 600, major code: 130 (Unknown), minor code: 3
…

Paulo

4

It worked for a while, then crashed again with these errors (after I clicked on the graph):

rqt_plot /laser_scan/ranges[100]
/usr/local/lib/python2.7/dist-packages/matplotlib/axis.py:1086: UserWarning: Unable to find pixel distance along axis for interval padding of ticks; assuming no interval padding needed.
warnings.warn("Unable to find pixel distance along axis "
/usr/local/lib/python2.7/dist-packages/matplotlib/axis.py:1096: UserWarning: Unable to find pixel distance along axis for interval padding of ticks; assuming no interval padding needed.
warnings.warn("Unable to find pixel distance along axis "
Traceback (most recent call last):
File “/opt/ros/kinetic/lib/python2.7/dist-packages/rqt_plot/data_plot/mat_data_plot.py”, line 107, in resizeEvent
self.figure.tight_layout()
File “/usr/local/lib/python2.7/dist-packages/matplotlib/figure.py”, line 2307, in tight_layout
pad=pad, h_pad=h_pad, w_pad=w_pad, rect=rect)
File “/usr/local/lib/python2.7/dist-packages/matplotlib/tight_layout.py”, line 349, in get_tight_layout_figure
pad=pad, h_pad=h_pad, w_pad=w_pad)
File “/usr/local/lib/python2.7/dist-packages/matplotlib/tight_layout.py”, line 117, in auto_adjust_subplotpars
fig.transFigure.inverted())
File “/usr/local/lib/python2.7/dist-packages/matplotlib/transforms.py”, line 1901, in inverted
self._inverted = Affine2D(inv(mtx), shorthand_name=shorthand_name)
File “/usr/local/lib/python2.7/dist-packages/numpy/linalg/linalg.py”, line 551, in inv
ainv = _umath_linalg.inv(a, signature=signature, extobj=extobj)
File “/usr/local/lib/python2.7/dist-packages/numpy/linalg/linalg.py”, line 97, in _raise_linalgerror_singular
raise LinAlgError(“Singular matrix”)
numpy.linalg.LinAlgError: Singular matrix

5

@paedusan,

I apologize for this error.

Please give us some time to solve this and get back to you.