Slices
======

Intro
-----

A quick way to look at data is to compute 2D data slice map.

Here is how it works: It first gets some sample points from a camera object, using a basic 2D Cartesian grid. Then those points are evaluated using the pymses point_sampler module. A sampling operator can eventually be applied on the data.

Example
-------

We first need to define a suitable camera::

    from pymses.analysis.visualization import Camera
    cam  = Camera(center=[0.5, 0.5, 0.5], line_of_sight_axis='z', region_size=[1., 1.],\
        up_vector='y', map_max_size=512, log_sensitive=True)

Using the amr data previously defined in :doc:`ug_read_amr`, we can get the map corresponding to the defined slice view. A logarithmic scale is here applied as it is defined in the camera object.

.. code-block:: python

    from pymses.analysis.visualization import SliceMap, ScalarOperator
    rho_op = ScalarOperator(lambda dset: dset["rho"])
    map = SliceMap(amr, cam, rho_op, z=0.4) # create a density slice map at z=0.4 depth position

The result can be seen using the matplotlib library::

    import pylab as P
    P.imshow(map)
    P.show()

.. plot:: pyplots/slice_density.py