Reading data from a raw VTK (.vtu) file

Question

I want to extract data arrays from a .vtu file using the Python VTK module. The file looks like this (the raw data at the end of the file is ommitted):

Answer 1

A more lightweight solution would be to use meshio (which I authored). It has no required dependencies except numpy. Install with

pip install meshio

and read the file with

import meshio

mesh = meshio.read("foo.vtu")
# mesh.points, mesh.cells, mesh.point_data, ...

Answer 2

You are not using the right reader, this is a .vtu file, you have to use the vtkXMLUnstructuredGridReader.

import vtk.vtk

# The source file
file_name = "path/to/your/file.vtu"

# Read the source file.
reader = vtk.vtkXMLUnstructuredGridReader()
reader.SetFileName(file_name)
reader.Update()  # Needed because of GetScalarRange
output = reader.GetOutput()
potential = output.GetPointData().GetArray("potential")