[Paraview] Find Data in Python

[Utkarsh Ayachit]

Christian,

O-oh! We can't have our users going mad now can we :). Guess we are
looking at this the wrong way, instead of working from the solution,
let's start with the problem/use-case. Can you describe your use-case
as simply as possibly. What's the goal here? What is the user doing?

Utkarsh

On Mon, Apr 19, 2010 at 11:20 AM, Christian Werner
<christian.werner at rwth-aachen.de> wrote:
> Does that mean that I have to create a selection with explicitly defining
> the points? Oh man... Then I can forget the whole thing anyway.
>
> Everything is so nice about Paraview, but this selection thing is driving me
> mad.
>
> It's still all about making it as easy as possible for the user to select
> objects out of Polydata and let a plugin analyze these objects. As it seems
> now, the user has to:
>
> 1) Ctrl+Click matching objects one after another (already dangerours,
> because you might forget to hold down Ctrl when selecting)
> 2) go to Filter->Recent->ExtractSelection
> 3) wait at least 3 seconds
> 4) call a plugin that writes the extracted points' coordinates and their ID
> to a file
> 5) call the analyzing plugin that reads out the file (to get the RegionID
> and coordinates) and does the analysing stuff (in ITK)
>
> I have found a way to do that "wait 3 seconds" in Python using a thread(!)
> which checks the time and joins after some seconds. Using sleep(5) simply
> froze everything and postponed the segmentation fault (which clearly comes
> from my writer that doesn't have input). Another possibility would be to
> modify vtkExtractSelection to suite my needs, but I won't do that, since I
> don't have time for that anymore. This workaround has to do.
>
> Anyway, Paraview, VTK and ITK are really nice, I am glad I found these
> open-source tools.
>
> Best regards,
> Christian
>
>
>
> Utkarsh Ayachit schrieb:
>>
>> Does your data have time? If not, you don't need to specify the
>> time=10000 attribute at all. So SelectionWriter is the thing that's
>> coming from your plugin? Does it support writing empty datasets?  Can
>> you attach a debugger and see where is crashes? Are you sure it's not
>> crashing in the writer? I dont' see why UpdatePipeline() on extract
>> selection would crash. Instead of using a macro, try manually typing
>> the text in the python shell to see exactly what line causes the
>> segfault.
>>
>> BTW, ExtractSelection needs two inputs: 'Input" and "Selection" where
>> Selection is set to the SelectionQuerySource proxy.
>>
>> Utkarsh
>>
>> On Mon, Apr 19, 2010 at 10:34 AM, Christian Werner
>> <christian.werner at rwth-aachen.de> wrote:
>>
>>>
>>> I am afraid UpdatePipeline doesn't help, even if I set the time to some
>>> high
>>> value. Paraview crashes right in the moment where I start this macro:
>>>
>>> extract=ExtractSelection(Input=ConnectivityFilter)
>>>
>>> UpdatePipeline(time= 10000, proxy=extract)
>>>
>>> mFilename = destPath + str( time() )
>>>
>>> swriter=SelectionWriter(Input=extract)
>>>
>>> swriter.FileName=mFilename
>>>
>>> swriter.UpdatePipeline()
>>>
>>>
>>> When I manually select Fiters->ExtractSelection and then do:
>>>
>>> mFilename = destPath + str( time() )
>>>
>>> swriter=SelectionWriter()
>>>
>>> swriter.FileName=mFilename
>>>
>>> swriter.UpdatePipeline()
>>>
>>>
>>> everything works fine.
>>>
>>>
>>>
>>> Utkarsh Ayachit schrieb:
>>>
>>>>
>>>> You can simply call UpdatePipeline() as follows:
>>>>
>>>> from paraview.simple import *
>>>> ....
>>>> UpdatePipeline(proxy=extractSelectionSource)
>>>>
>>>> This will update the extract selection filter explicitly. Look at
>>>> help(UpdatePipeline) for details.
>>>>
>>>> Utkarsh
>>>>
>>>>
>>>> On Sun, Apr 18, 2010 at 3:38 PM, Christian Werner
>>>> <christian.werner at rwth-aachen.de> wrote:
>>>>
>>>>
>>>>>
>>>>> Hi Utkarsh,
>>>>>
>>>>> these are great news. I tried the python trace but not in combination
>>>>> with
>>>>> the extraction (what I acutally do need anyway....)
>>>>>
>>>>> As you might remember I am working around the "lack" of possibilty to
>>>>> select
>>>>> whole objects (cells with same RegionID). With the given
>>>>> SelectionQuerySource this workaround is complete.
>>>>>
>>>>> There remains one issue: At some point I call an ExtractSelection() in
>>>>> Python that is followed by a call to a vtk-Plugin (which writes the
>>>>> point
>>>>> data of the selected points to disk). The resulting file is empty,
>>>>> because
>>>>> the Extraction takes a few seconds and obviously the plugin has no
>>>>> valid
>>>>> input when being executed. Paraview also crashes as a consequence. When
>>>>> I
>>>>> am
>>>>> doing this manually (trigger ExtractSelection, wait until it's done,
>>>>> call
>>>>> the vtk Plugin to write the point data) everything works fine. I could
>>>>> just
>>>>> go ahead and do a dull time.sleep(3) between the extraction and the
>>>>> call
>>>>> to
>>>>> the plugin, but this certainly isn't good programming style.
>>>>>
>>>>> What can I do instead?
>>>>>
>>>>>
>>>>> Best regards,
>>>>> Christian
>>>>>
>>>>>
>>>>> Utkarsh Ayachit wrote:
>>>>>
>>>>>
>>>>>>
>>>>>> Yes, you can use the "SelectionQuerySource" to construct your query as
>>>>>> follows:
>>>>>>
>>>>>> selection_source_540 = SelectionQuerySource( InsideOut=0,
>>>>>> ArrayName='', HierarchicalLevel=-1, ProcessID=-1, ContainingCells=0,
>>>>>> DoubleValues=None, HierarchicalIndex=-1, FieldType='CELL',
>>>>>> ArrayComponent=0, Operator='IS_ONE_OF', TermMode='ID',
>>>>>> CompositeIndex=-1, IdTypeValues=0 )
>>>>>>
>>>>>> You can use the python trace recorder functionality to determine how
>>>>>> to create the query. You will, however have to "Extract Selection"
>>>>>> from the query (and hit apply) before the selection_source object will
>>>>>> appear in the trace.
>>>>>>
>>>>>> Utkarsh
>>>>>>
>>>>>>
>>>>>> On Sat, Apr 17, 2010 at 9:32 AM, Christian Werner
>>>>>> <christian.werner at rwth-aachen.de> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>> Hello!
>>>>>>>
>>>>>>> Is there any chance that the new Edit->Find Data functionality is
>>>>>>> available
>>>>>>> in Python-Scripting?
>>>>>>>
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Christian
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>>>>>>>
>>>>>>>
>>>>>>>
>>>>>
>>>>>
>>>
>>>
>
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