[Paraview] Python + ParaView

Nico Schlömer nico.schloemer at gmail.com
Thu Jun 16 10:19:02 EDT 2011 

Progress!
Thanks to the incredibly helpful Trance functionality, I understand
now that something like

=================== *snip* ===================
    calc1 = pv.Calculator( ResultArrayName = '|psi|^2' )
    calc1.AttributeMode = 'point_data'
    calc1.Function = 'psi__X^2 + psi__Y^2'

    [...]
    psi_lookup_table = pv.GetLookupTableForArray( '|psi|^2', 1 )
                                         )
    data_representation.ColorArrayName = '|psi|^2'
=================== *snap* ===================

will get me pretty close to where I want to be; except that Function()
is limited to whatever help( calc1 ) just told me. -- Conditionals /
atan2()?

--Nico




On Thu, Jun 16, 2011 at 3:45 PM, Nico Schlömer <nico.schloemer at gmail.com> wrote:
> Also, when
>
> ======================== *snip* ========================
>>>>
>>>> import paraview.simple
> paraview version 3.10.1, Date: 2011-01-28
>>>> calc1 = paraview.simple.servermanager.filters.Calculator()
>>>> help( calc1 )
>>>>
> ======================== *snip* ========================
>
> I don't see how to apply math.atan2() to two components of an input
> vector: Exactly those functions appear to be documented which are
> available in the GUI. Hmm...
>
> --Nico
>
>
>
> On Thu, Jun 16, 2011 at 3:24 PM, Nico Schlömer <nico.schloemer at gmail.com> wrote:
>>> See the manual for the syntax.
>>
>> Where can I find that? The ParaView User's Guide
>> <www.paraview.org/files/v1.6/ParaViewUsersGuide.PDF> isn't too verbose
>> on any of that.
>> The Wiki, on the other hand, seems to contain a fair amount of
>> examples. Specifically, I've looked at
>> <http://www.paraview.org/Wiki/Python_Programmable_Filter> to see about
>> programmable filters.
>>
>> Unfortunately, this hasn't gotten me very far, as I'm lacking
>> understanding of the entities used in the examples.
>> Questions I asked myself were:
>>  * What do I need to do to fetch my point data:
>> self.GetPolyDataInput()? self.GetInputDataObject(0, 0)? Or simply
>> self.GetInput()?
>>  * How do I access point data then?
>>  * Do I have to create a new vector and feed this into some sort of
>> output thing?
>>
>> Is there a documentation as to what methods are available for those types?
>>
>> The input file is Exodus, if that makes any difference.
>>
>> If there's a tutorial for this kind of stuff, I'll be happy to go
>> through it; otherwise I'd appreciate your help here.
>>
>> Cheers,
>> Nico
>>
>>
>>
>>
>>
>>
>> On Wed, Jun 8, 2011 at 6:17 PM, David E DeMarle
>> <dave.demarle at kitware.com> wrote:
>>> Also the standard calculator does have conditionals, there just isn't a
>>> button corresponding to them on the UI. See the manual for the syntax.
>>> David E DeMarle
>>> Kitware, Inc.
>>> R&D Engineer
>>> 28 Corporate Drive
>>> Clifton Park, NY 12065-8662
>>> Phone: 518-371-3971 x109
>>>
>>>
>>> On Wed, Jun 8, 2011 at 12:16 PM, David E DeMarle <dave.demarle at kitware.com>
>>> wrote:
>>>>
>>>> The python programmable filter (and the easier to use python programmable
>>>> calculator variant of that) will get you beyond all of those limitations.
>>>> David E DeMarle
>>>> Kitware, Inc.
>>>> R&D Engineer
>>>> 28 Corporate Drive
>>>> Clifton Park, NY 12065-8662
>>>> Phone: 518-371-3971 x109
>>>>
>>>>
>>>> On Wed, Jun 8, 2011 at 12:11 PM, Nico Schlömer <nico.schloemer at gmail.com>
>>>> wrote:
>>>>>
>>>>> > 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
>>>>> >>>> _______________________________________________
>>>>> >>>> Powered by www.kitware.com
>>>>> >>>>
>>>>> >>>> Visit other Kitware open-source projects at
>>>>> >>>> http://www.kitware.com/opensource/opensource.html
>>>>> >>>>
>>>>> >>>> Please keep messages on-topic and check the ParaView Wiki at:
>>>>> >>>> http://paraview.org/Wiki/ParaView
>>>>> >>>>
>>>>> >>>> Follow this link to subscribe/unsubscribe:
>>>>> >>>> http://www.paraview.org/mailman/listinfo/paraview
>>>>> >>>>
>>>>> >>>
>>>>> >>
>>>>> >
>>>>> _______________________________________________
>>>>> Powered by www.kitware.com
>>>>>
>>>>> Visit other Kitware open-source projects at
>>>>> http://www.kitware.com/opensource/opensource.html
>>>>>
>>>>> Please keep messages on-topic and check the ParaView Wiki at:
>>>>> http://paraview.org/Wiki/ParaView
>>>>>
>>>>> Follow this link to subscribe/unsubscribe:
>>>>> http://www.paraview.org/mailman/listinfo/paraview
>>>>
>>>
>>>
>>
>

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