[vtkusers] Extracting cell connectivity from a vtk file

[Berk Geveci]

You should be able to do:

ug = r.GetOutput()
ncells = ug.GetNumberOfCells()
for i in xrange(ncells):
  cell = ug.GetCell(i)

The key is to call GetCell() on the unstructured grid not the cell
array returned by GetCells().

-berk


On Fri, Sep 25, 2009 at 11:37 AM, Eric Mark (CISD/CIV)
<emark at arl.army.mil> wrote:
> Hello all,
>
> I'm using python with vtk 5.2.1 and am trying to read the connectivity list
> from a vtk file and write it back out in a different format.    I'm able to
> read the point data but I'm not having any success in reading the
> connectivity data.    I would like to be able to print out a connectivity
> list in the same manner that I'm using below to print the points.  However
> it seems that GetCell or GetNextCell methods are not available from Python.
>  Am I doing something wrong or is there an alternate way of doing this?
>
> Thanks,
>
> Eric
>
> Here's the code:
>
> fn = "test.vtk"
> r = vtkUnstructuredGridReader()
>
> r.SetFileName(fn)
> r.Update()
> points = r.GetOutput().GetPoints()
>
> print "Number of Points: " ,  points.GetNumberOfPoints()
> i = 0
> while(i < points.GetNumberOfPoints()) :
>    print "Next Point : %d, %s " % (i + 1, points.GetPoint(i))
>    i = i + 1
>
> numcells = r.GetOutput().GetNumberOfCells()
> print "Number Of Cells: ", numcells
> cells = r.GetOutput().GetCells()
> print "Cells Var contains: ", cells
> print "Cells.GetSize : ", cells.GetSize()
> print "Cells.GetSize : ", cells.GetNumberOfConnectivityEntries()
> print "What Can I Do With Cells? :", dir(cells)
> j = 0
> cells.SetTraversalLocation(j)
> print "NextCell", cells.GetOutput().GetCell(j)
> #print "Check Array: ",  r.GetOutput().GetCells()
> while(j < cells ):
>    #print " %d, %s " % (j + 1, cells.GetNextCell())
>    j = j + 1
>
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