[Paraview] Python + ParaView

[Nico Schlömer]

> If you want to do arbitrary arithmetic, you will have to first
> generate the array using something like a "Calculator" filter and then
> color using the generated array.

Oh, if I remember correctly I did look into this before, and found the
calculator filter too limited on the arithmetics that you could
perform. Is it still the case that you have a set of like ten
functions (add, multiply, sine, cosine,...) to mix and match? I need
to to something like

for x in data_values:
    if x[0] > 0 and x[1] > 0
        return bla
    elseif ...

-- atan2() that is.


> Yes, RGBPoints defines the mapping between scalar and color. It's a
> list of 4 tuples (scalar, r, g, b), repeated sequentially.

Hm, I'll look into it. Where's the proper spot for documentation of this?

Cheers,
Nico







On Wed, Jun 8, 2011 at 5:25 PM, Utkarsh Ayachit
<utkarsh.ayachit at kitware.com> wrote:
> Magnitude corresponds to the magnitude of a vector, so yes, it takes
> the square root.
>
> If you want to do arbitrary arithmetic, you will have to first
> generate the array using something like a "Calculator" filter and then
> color using the generated array.
>
> Yes, RGBPoints defines the mapping between scalar and color. It's a
> list of 4 tuples (scalar, r, g, b), repeated sequentially.
>
> Utkarsh
>
> On Wed, Jun 8, 2011 at 11:19 AM, Nico Schlömer <nico.schloemer at gmail.com> wrote:
>> Thanks for the hints.
>>
>> The Trace function in indeed quite useful in that it get you where you
>> want to be. When looking at the code there's still a lot of me to
>> understand though, the GetLookupTableForArray() call seems to be
>> crucial for example.
>>
>>  * The VectorMode='Magnitude' parameter seems to be responsible for
>> merging the two components into one scalar, but I'm not quite sure how
>> this is done: with a sqrt() or without? Is is possible to customize
>> this? I'd like to have something like ATAN2 there as well.
>>
>>  * Is the RGBPoints=[0.0, 0.0, 0.0, 0.0, 1.0, 1.0, 1.0, 1.0],
>> parameter responsible for the colormap?
>>
>> Cheers,
>> Nico
>>
>>
>>
>>
>>
>> On Wed, Jun 8, 2011 at 3:13 PM, Utkarsh Ayachit
>> <utkarsh.ayachit at kitware.com> wrote:
>>> The following wiki page talks about how to color using arrays:
>>> http://www.paraview.org/Wiki/ParaView/Python_Scripting#Representations_and_Views
>>>
>>> The easiest way to figure out Python code equivalents is to use the
>>> Trace functionality to generate python trace files for actions
>>> performed in the GUI (accessible from Tools menu). You "Start Trace",
>>> do a set of actions and then "Stop Trace" and you should be able to
>>> view the resulting Python code.
>>>
>>> Utkarsh
>>>
>>>
>>>
>>> On Wed, Jun 8, 2011 at 9:05 AM, Nico Schlömer <nico.schloemer at gmail.com> wrote:
>>>> Hi,
>>>>
>>>> I'm just taking first steps with ParaView's Python interface and
>>>> figured out so far that
>>>>
>>>> ================ *snip* ================
>>>> exodusReader = ExodusIIReader( FileName="solution.e" )
>>>> Show( exodusReader )
>>>> Render()
>>>> ================ *snap* ================
>>>>
>>>> would plot the mesh that is stored in the ExodusII file solution.e,
>>>> and that can play around with GetActiveView() to adjust camera angles
>>>> and such.
>>>>
>>>> What I haven't found out though is how to plot actual point data. I get
>>>>
>>>>
>>>>>>> exodusReader.PointData[:]
>>>> [Array: GlobalNodeId, Array: PedigreeNodeId, Array: A, Array: psi,
>>>> Array: thickness]
>>>>
>>>> and l'm looking at the 2-component array "psi". For example, I'd like
>>>> to do something like
>>>>
>>>>    res =  sqrt( component1**2 + component2**2 )
>>>>
>>>> and have res[:] rendered on the mesh with a certain color map.
>>>>
>>>> Any hints?
>>>>
>>>> Cheers,
>>>> Nico
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>>
>