Determine if legacy VTK file is valid using Python

Question

I need to read a legacy VTK file with Python. I want to use the vtk module. I've been mostly successful, but I need to be able to detect if the VTK file is valid or not before continuing and I cannot find a type-bound procedure or attribute that will do this. Here's a minimal example of the VTK file.

# vtk DataFile Version 2.0
Scalar Data
ASCII
DATASET UNSTRUCTURED_GRID
POINTS      12 double
 -6.35000002E-03  0.00000000E+00  0.00000000E+00
  0.00000000E+00  0.00000000E+00  0.00000000E+00
 -6.35000002E-03  6.35000002E-03  0.00000000E+00
  0.00000000E+00  6.35000002E-03  0.00000000E+00
 -6.35000002E-03  0.00000000E+00  3.86600012E-02
  0.00000000E+00  0.00000000E+00  3.86600012E-02
 -6.35000002E-03  6.35000002E-03  3.86600012E-02
  0.00000000E+00  6.35000002E-03  3.86600012E-02
 -6.35000002E-03  0.00000000E+00  3.86600012E-02
  0.00000000E+00  0.00000000E+00  3.86600012E-02
 -6.35000002E-03  6.35000002E-03  3.86600012E-02
 -6.35000002E-03  6.35000002E-03  3.86600012E-02
CELLS         2        18
         8         0         1         2         3         4         5         6         7
         8         8         9        10        11        12        13        14        15
CELL_TYPES       2
11
11
CELL_DATA       2
SCALARS testdata float
LOOKUP_TABLE default
  1.0000E+00

The error in this file is that there is only 1 cell data given when the header indicates there should be two. Here's my python file to read this data.

import vtk 
from vtk.util import numpy_support as VN

f1=vtk.vtkUnstructuredGridReader()
f1.SetFileName('test.vtk')
f1.ReadAllScalarsOn()
f1.Update()
arr=VN.vtk_to_numpy(f1.GetOutput().GetCellData().GetArray('testdata'))
print arr 

And here's the output:

Generic Warning: In /home/vagrant/pisi/tmp/VTK-6.3.0-3/work/VTK-6.3.0/IO/Legacy/vtkDataReader.cxx, line 1379
Error reading ascii data. Possible mismatch of datasize with declaration.


[  1.00000000e+00   7.84727140e-44]

So you see it is detecting the inconsistency, but it doesn't crash the code. Instead, my numpy array gets a bogus value in the array. Is there a way to get a read error back from vtk so I can handle it? Or is there some procedure that will parse the VTK file and tell me if it's valid before reading it?

Answer 1

尝试使用数据读取器类的IsFileValid或IsFileUnstructuredGrid方法。