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.. _running-mlab-scripts:
Running mlab scripts
---------------------
Mlab, like the rest of Mayavi, is an interactive application. If you are
not already in an interactive environment (see next paragraph), to
interact with the figures or the rest of the drawing elements, you need
to use the :func:`show` function. For instance, if you are writing a
script, you need to call :func:`show` each time you want to display one
or more figures and allow the user to interact with them.
Using mlab interactively
~~~~~~~~~~~~~~~~~~~~~~~~~
Using IPython_, mlab instructions can be run interactively, or in
scripts using IPython_'s ``%run`` command::
In [1]: %run my_script
You need to start IPython_ with the `--gui=qt` option. In this
environment, the plotting commands are interactive: they have an
immediate effect on the figure, alleviating the need to use the
:func:`show` function.
.. _EPD: http://www.enthought.com/products/epd.php
Mlab can also be used interactively in the Python shell of the mayavi2
application, or in any interactive Python shell of wxPython-based
application (such as other Envisage-based applications, or SPE, Stani's
Python Editor).
Using together with Matplotlib
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you want to use Matplotlib's interactive plotting with Mayavi's
mlab in IPython you should:
* start IPython with::
$ ipython --matplotlib=qt
* alternatively, start IPython with the `--gui=qt` option::
$ ipython --gui=qt
and **before** importing any matplotlib modules, enter the
following Python commands::
>>> import matplotlib
>>> matplotlib.use('Qt4Agg')
>>> matplotlib.interactive(True)
* one could also use the ``--pylab`` option to IPython as
follows::
$ ipython --pylab=qt
If you want matplotlib and mlab to work together by default in IPython,
you can change you default matplotlib backend, by editing the
`~/.matplotlib/matplotlibrc` to add the following line::
backend : Qt4Agg
If for some reason, the Qt backend does not work, you can use the wx
backend. To do this you may do::
$ ETS_TOOLKIT=wx
$ ipython --gui=wx
Note that as far as Mayavi is concerned, it chooses the appropriate
toolkit using the ``ETS_TOOLKIT`` environment variable. If this is
not set, the supported toolkits are tried in a version-dependent order
until one succeeds. With recent releases of traitsui_, the default is
Qt. The possible options for ``ETS_TOOLKIT`` are:
- `qt4`: to use the Qt backend (either PySide or PyQt4),
- `wx`: to use wxPython,
- `null`: to use no UI toolkit.
.. _traitsui: http://github.com/enthought/traitsui
.. topic:: Capturing mlab plots to integrate in pylab
Starting from Mayavi version 3.4.0, the mlab :func:`screenshot` can
be used to take a screenshot of the current figure, to integrate in a
matplotlib plot.
In scripts
~~~~~~~~~~~~~~~~~
Mlab commands can be written to a file, to form a script. This script
can be loaded in the Mayavi application using the *File->Open file* menu
entry, and executed using the *File->Refresh code* menu entry or by
pressing ``Control-r``. It can also be executed during the start of the
Mayavi application using the ``-x`` command line switch.
As mentioned above, when running outside of an interactive environment,
for instance with `python myscript.py`, you need to call the
:func:`show` function (as shown in the demo_ above) to pause your script
and have the user interact with the figure.
.. _demo:
:ref:`mlab-demo`
You can also use :func:`show` to decorate a function, and have it run in
the event-loop, which gives you more flexibility::
from mayavi import mlab
from numpy import random
@mlab.show
def image():
mlab.imshow(random.random((10, 10)))
With this decorator, each time the `image` function is called, `mlab`
makes sure an interactive environment is running before executing the
`image` function. If an interactive environment is not running, `mlab`
will start one and the image function will not return until it is closed.
..
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