[vtkusers] importing unstructured grid data from numpy array

[Florian Bruckner]

OK, sounds good. but I cannot find the numpy_to_vtkIdTypeArray()
function. should it also be in numpy_support module
(/usr/lib/pymodules/python2.6/vtk/util/numpy_support.py) ?

the python version i use is fairly new (Python 2.6.5 (r265:79063, Apr 16
2010, 13:57:41)) so i think it should be there but it is not? 

do i have to install any additional packages?

thanks
FloB


On Wed, 2010-05-26 at 06:59 -0400, Eric E. Monson wrote:
> Hey Florian,
> 
> That's what the numpy_to_vtkIdTypeArray() is for -- creating a vtkIdTypeArray. You can't just cast another type of VTK array to IdType, so that's why they have a special function for it. As another note, you can also get vtkIntArray out of numpy_to_vtk() if you specifically send in an int type numpy array.
> 
> Hope that helps,
> -Eric
> 
> On May 26, 2010, at 4:14 AM, Florian Bruckner wrote:
> 
> > thanks for your help at first. 
> > 
> > your example works well, but I have still troubles when I want to insert
> > the cell data. I'm still a python newbie, but I could figure out that
> > numpy_to_vtk gives me a vtkFloatArray whereas the SetCells() function of
> > my vtkCellArray requires a vtkIdTypeArray.
> > 
> > is there something like a typecast operator in python or is there a
> > conversion function available somewhere?
> > 
> > my code looks like the following:
> >>> tets = array([[0,1,2,3]])
> >>> ccV = VN.numpy_to_vtk(tets, deep=True)
> >>> cells = vtk.vtkCellArray()
> >>> cells.SetCells(1, ccV)  ==> error
> >>> ug.SetCells(VTK_TETRA, cells)
> > 
> > bye
> > FloB
> > 
> > 
> > On Tue, 2010-05-25 at 09:31 -0400, Eric E. Monson wrote:
> >> Hey Florian,
> >> 
> >> There are pretty easy ways to do it, but I haven't used tvtk for a while, so I don't remember the comparison. You can do something like this:
> >> 
> >> # ===================================
> >> from vtk.util import numpy_support as VN
> >> import vtk
> >> import numpy as N
> > 
> >> ug = vtk.vtkUnstructuredGrid()
> >> pts = vtk.vtkPoints()
> >> 
> >> # Create the points array and set the UG to use them
> >> pp = N.random.rand(10,3)
> >> ppV = VN.numpy_to_vtk(pp, deep=True)
> >> pts.SetData(ppV)
> >> ug.SetPoints(pts)
> >> 
> >> # Add an attribute array (scalars) to the UG
> >> aa = N.random.rand(10)
> >> aaV = VN.numpy_to_vtk(aa,deep=True)
> >> aaV.SetName('Attribute1')
> >> ug.GetPointData().AddArray(aaV)
> >> # ===================================
> >> 
> >> So it's not too bad. Also, note that there is a vtk_to_numpy() and a numpy_to_vtkIdTypeArray(), which often comes in quite handy for me.
> >> 
> >> Talk to you later,
> >> -Eric
> >> 
> >> ------------------------------------------------------
> >> Eric E Monson
> >> Duke Visualization Technology Group
> >> 
> >> 
> >> On May 25, 2010, at 5:44 AM, Florian Bruckner wrote:
> >> 
> >>> hello,
> >>> 
> >>> I would need a method to read unstructured grid data from a numpy array.
> >>> Does anyone know a function like vtkImageInputFrom/ExportToArray.py that
> >>> also handles unstructured grids? or is there a possibility to transform
> >>> image data to unstructured grids?
> >>> 
> >>> i only found the tvtk library, but in order to use it I will have to
> >>> install the whole ETS project. In addition the documentation of this
> >>> library mention that it is more 'pytonic' to use tvtk but that it should
> >>> also be possible to do the same things with pure vtk.
> >>> 
> >>> thanks 
> >>> FloB
> >>> 
> >>> 
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