Mayavi doesn't run from within Spyder: complains about "ValueError: API 'QString' ..."

Question

I am unable to run/use Mayavi library from within Spyder IDE. I have described the problem below. Any help will be very useful. (Thank you very much in advance.)

Steps to reproduce the problem:

1. Just importing the Mayavi library in a script (for example using "import mayavi.mlab as mlab") and executing the script will reproduce this problem.
2. I am including a test code (note that this code is an example code from the Mayavi website) here to reproduce the problem:

code

from numpy import sin, cos, mgrid
import mayavi.mlab as mmlab

def f(x,y):
  return sin(x + y) + sin(2*x - y) + cos(3*x + 4*y)
        
x,y = mgrid[-7.:7.05:0.01, -5.:5.05:0.05]
z = f(x,y)
s = mmlab.contour_surf(x,y,z)
mmlab.show()

Expected output and the Error:

Expected output: A Mayavi figure window with the figure. What I see instead: The following Value error (I am including the full sequence of message in order to be explicit)in the console window:

-------------------------- Beginning of error message ------------------

Traceback (most recent call last):
  File "C:\PROGRAMSANDEXPERIMENTS\PYTHON\MayaviScripts\Learning\testMayavi.py", line 2, in <module>
    import mayavi.mlab as mmlab
  File "C:\Python27\lib\site-packages\mayavi\mlab.py", line 27, in <module>
    from mayavi.tools.camera import view, roll, yaw, pitch, move
  File "C:\Python27\lib\site-packages\mayavi\tools\camera.py", line 25, in <module>
    from engine_manager import get_engine
  File "C:\Python27\lib\site-packages\mayavi\tools\engine_manager.py", line 12, in <module>
    from mayavi.preferences.api import preference_manager
  File "C:\Python27\lib\site-packages\mayavi\preferences\api.py", line 4, in <module>
    from preference_manager import preference_manager
  File "C:\Python27\lib\site-packages\mayavi\preferences\preference_manager.py", line 29, in <module>
    from traitsui.api import View, Group, Item
  File "C:\Python27\lib\site-packages\traitsui\api.py", line 35, in <module>
    from .editors.api import (ArrayEditor, BooleanEditor, ButtonEditor,
  File "C:\Python27\lib\site-packages\traitsui\editors\__init__.py", line 22, in <module>
    from .api import (toolkit, ArrayEditor, BooleanEditor, ButtonEditor,
  File "C:\Python27\lib\site-packages\traitsui\editors\api.py", line 10, in <module>
    from .code_editor import CodeEditor
  File "C:\Python27\lib\site-packages\traitsui\editors\code_editor.py", line 36, in <module>
    class ToolkitEditorFactory ( EditorFactory ):
  File "C:\Python27\lib\site-packages\traitsui\editors\code_editor.py", line 48, in ToolkitEditorFactory
    mark_color = Color( 0xECE9D8 )
  File "C:\Python27\lib\site-packages\traits\traits.py", line 487, in __call__
    return self.maker_function( *args, **metadata )
  File "C:\Python27\lib\site-packages\traits\traits.py", line 1183, in Color
    return ColorTrait( *args, **metadata )
  File "C:\Python27\lib\site-packages\traitsui\toolkit_traits.py", line 7, in ColorTrait
    return toolkit().color_trait( *args, **traits )
  File "C:\Python27\lib\site-packages\traitsui\toolkit.py", line 109, in toolkit
    _toolkit = _import_toolkit(ETSConfig.toolkit)
  File "C:\Python27\lib\site-packages\traitsui\toolkit.py", line 51, in _import_toolkit
    return __import__( name, globals=globals(), level=1 ).toolkit
  File "C:\Python27\lib\site-packages\traitsui\qt4\__init__.py", line 18, in <module>
    import pyface.qt
  File "C:\Python27\lib\site-packages\pyface\qt\__init__.py", line 35, in <module>
    prepare_pyqt4()
  File "C:\Python27\lib\site-packages\pyface\qt\__init__.py", line 17, in prepare_pyqt4
    sip.setapi('QString', 2)
  ValueError: API 'QString' has already been set to version 1

---------------------------- End of error message --------------------

My environment(s) are the following:

This issue has been observed at-least in the following two environments:

Environment 1:

Description: Spyder and all other components were installed using the Pythonxy distribution (Py(x,y)-2.7.2.3.exe) on a Windows 7, 32 bit machine). Spyder Version: 2.1.9 Python Version: 2.7.2 (32 bit) Qt Version: 4.7.4, PyQt4 (API v1) 4.8.6 on Windows Mayavi Version: 4.1.0

Environment 2:

Description: On a separate machine running 64 bit Windows 7, I have installed 64-bit version of the Enthought EPD distribution. So it is running 2.7.3 (x64) version of Python distribution. Since the EPD package doesn't include Spyder, I manually installed Spyder after installing PyQt GPLv4.9.4.
Spyder Version: 2.1.11 Python Version: 2.7.3 (64 bit) Qt Version: 4.8.2, PyQt4 (API v2) 4.9.4 on Windows Mayavi Version: 4.2.0

Additional information:

I am sure that the code is fine, as the script produces the expected output when executed "outside" spyder environment. For example, using IPython shell.

Thank you.

Answer 1

Thanks Avaris for your response.

I have a solution for now (I am not sure of it as a "fix"). I modified the following setting in Tools->Preferences->Console->External Modules->Enthought Tool Suite->ETS_TOOLKIT: change from Qt4 to wx. After changing this setting, I am able to execute code with Mayavi library and Mayavi plots directly from within Spyder.

Answer 2

for linux users, the answer by imranal in this issues can be referenced to.

just add export ETS_TOOLKIT=qt4 to a new line in ~/.bashrc will do the trick. don't forget to source the ~/.bashrc file!

Answer 3

According to this and this the error can be fixed by activating the Ignore API change errors (sip.setapi) checkbox in Preferences > Console > External Modules.

I have tested that it does work with Spyder 2.1.11.