I've been given a legacy format vtk file (I think its an unstructured grid) and I'd like to read it in with python and output a .npy file instead, since I know how to deal with that.
The file is a dump from ATHENA and so has density, velocity, magnetic field along with the coordinates.
I'm very much a procedural programmer, so all these objects are confusing...
Answer
Here is the solution that I came up with, the trick was turning on ReadAllVectorsOn().
import numpy
from vtk import vtkStructuredPointsReader
from vtk.util import numpy_support as VN
reader = vtkStructuredPointsReader()
reader.SetFileName(filename)
reader.ReadAllVectorsOn()
reader.ReadAllScalarsOn()
reader.Update()
data = reader.GetOutput()
dim = data.GetDimensions()
vec = list(dim)
vec = [i-1 for i in dim]
vec.append(3)
u = VN.vtk_to_numpy(data.GetCellData().GetArray('velocity'))
b = VN.vtk_to_numpy(data.GetCellData().GetArray('cell_centered_B'))
u = u.reshape(vec,order='F')
b = b.reshape(vec,order='F')
x = zeros(data.GetNumberOfPoints())
y = zeros(data.GetNumberOfPoints())
z = zeros(data.GetNumberOfPoints())
for i in range(data.GetNumberOfPoints()):
x[i],y[i],z[i] = data.GetPoint(i)
x = x.reshape(dim,order='F')
y = y.reshape(dim,order='F')
z = z.reshape(dim,order='F')