[Paraview] Programmable filter issue with modifying grid data

[stofem]

Hi,

Thanks for your help both of you.

Cheers for pointing out my Cell-Point mistake Burlen, I actually am
increasing my extents (extent[1]+1 for example) to compensate for this, but
I did make a mistake in my final call

*out.GetCellData().AddArray(newArray)*
*
*
which should be getting PointData, not CellData. My filter now works as
planned :)

However I am interested in some of your comments. Being a new
Python/Paraview/VTK programmer I would appreciate a bit of further advice:

In the two first loops you are treating 'i' as the slowest changing
> direction when it is the fastest. That will kill your performance. Last loop
> has correct order.


I agree that i should be the fastest changing index in some sense, but
because I have to step over all values of i,j,k to read the entire array
into my python array, I don't see why any other looping direction would be
quicker?

You may want to avoid the range function in your loop since if my
> recollection is correct that explicitly constructs a list of values


I think you're right, it does seem to construct a list explicitly, but I
don't really know what the alternative is?

Thanks again.

Looking forward to seeing that new filter built in!

On Sat, Oct 29, 2011 at 3:08 AM, Burlen Loring <bloring at lbl.gov> wrote:

> **
> Hi,
>
> You haven't configured your output, assuming rectilinear grid you need to
> set the extent and provide coordinate arrays.
>
> You are indexing a point based array with cell based index, so the lookup
> you make into vtkVarray is incorrect. 'Extent' tells you the number of
> cells, not the number of points, for that use 'Dimensions' or add one in
> each direction. Your script would certainly be more readable if you used
> some variables such as:
>
> ncx = ext[1]-ext[0]+1
> ncy = ext[3] -ext[2] +1
> ncxy = nx*ny
> ncz = ext[5]-ext[4] +1
> cidx = k*nxy + j*nx+i
>
> for number of cells and a cell array index.
>
> In the two first loops you are treating 'i' as the slowest changing
> direction when it is the fastest. That will kill your performance. Last loop
> has correct order.
>
> You may want to avoid the range function in your loop since if my
> recollection is correct that explicitly constructs a list of values.
>
> I hope this is helpful.
> Burlen
>
>
> On 10/26/2011 10:41 PM, Mr FancyPants wrote:
>
> Hi there,
>
>  I am trying to write a programmable filter which will take my
> RectilinearGrid data and modify one of the data arrays. Specifically I want
> to sum over one dimension. I have written something to do this, but my data
> comes out garbled.
>
>  Below is my code. Basically all I am doing is extracting all the data,
> doing my sum over the z direction and then putting this data into another
> rectilinear grid.
>
>
>  *data=self.GetInput()*
> *out=self.GetOutput()*
> *extent=data.GetExtent()*
> *vtkVarray=data.GetPointData().GetArray('velocity')*
> *
> *
> *import numpy*
> *pyVarray_x = numpy.zeros([extent[1]+1,extent[3]+1,extent[5]+1])*
> *pyVarray_y = numpy.zeros([extent[1]+1,extent[3]+1,extent[5]+1])*
> *pyVarray_z = numpy.zeros([extent[1]+1,extent[3]+1,extent[5]+1])*
> *
> *
> *for i in range(0,extent[1]+1):*
> * for j in range(0,extent[3]+1):*
> * for k in range(0,extent[5]+1):*
> * tup=vtkVarray.GetTuple(i+j*(extent[1]+1)+k*(extent[1]+1)*(extent[3]+1))*
> * pyVarray_x[i,j,k]=tup[0]*
> * pyVarray_y[i,j,k]=tup[1]*
> * pyVarray_z[i,j,k]=tup[2] *
> *
> *
> *
> *
> *
> *
> *pyVarray_x_noz = numpy.zeros([extent[1]+1,extent[3]+1,1])*
> *pyVarray_y_noz = numpy.zeros([extent[1]+1,extent[3]+1,1])*
>  *pyVarray_z_noz = numpy.zeros([extent[1]+1,extent[3]+1,1])*
> *
> *
> *for i in range(0,extent[1]+1):*
> * for j in range(0,extent[3]+1):*
> * pyVarray_x_noz[i,j]=pyVarray_x[i,j,:].sum()*
> * pyVarray_y_noz[i,j]=pyVarray_y[i,j,:].sum()*
> * pyVarray_z_noz[i,j]=pyVarray_z[i,j,:].sum()*
> *
> *
> *newArray=vtk.vtkDoubleArray()*
> *newArray.SetName("test")*
> *newArray.SetNumberOfComponents(3)*
> *
> *
> *print newArray*
> *
> *
> *for k in range(0,extent[5]+1):*
> * for j in range(0,extent[3]+1):*
> * for i in range(0,extent[1]+1):*
> * tup0=pyVarray_x_noz[i,j]*
>  * tup1=pyVarray_y_noz[i,j]*
> * tup2=pyVarray_z_noz[i,j]*
> * tup=(tup0,tup1,tup2)*
> * newArray.InsertNextTuple((tup0,tup1,tup2))*
> *
> *
> *print newArray*
> *print vtkVarray*
> *
> *
> *out.GetCellData().AddArray(newArray)*
>  *
> *
> I have no idea whats going wrong with this. Any help is much appreciated,
> new to using paraview.
>
>  Thanks, James
>
>
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