Saving data as .csv files

MFiX
#21

Hi, Justin, May I ask a question? I have used the code obtaining the information about “Diameter” , but how can I obtain the coordinate of each particle from vtp files? The coordinate is not a component name.

#22

you could store the particle x y z coordinates as 3 distinct DES_USR_VAR that can thus be saved as vtk along with velocity, diameter etc

#23

Thanks very much. But in this case, I will recalculate all the cases.

#24

The points (particle locations) are stored in the vtp files differently then the variable arrays. You can access the points like this:

import numpy as np
import vtk
from vtk.util.numpy_support import vtk_to_numpy

particle_reader= vtk.vtkXMLPolyDataReader()
particle_reader.SetFileName(fname)
particle_reader.Update()
data = particle_reader.GetOutput()

# get the positions!
particle_positions = vtk_to_numpy(data.GetPoints().GetData())

FYI, I learned most of this from reading the VTK docs and the examples.

#25

Thanks very much for your valuable instructions. It really helps me.

#26

@onlyjus How can I get the velocity of the particles? I can get the positions of the particles by the piece of code you provided, but I am not able to get the velocity?

#27

If you are saving the particle velocity in the VTK files, you can access that variable for each particle.

To see the array names, you can do something like this (untested):

particle_reader = (
        vtk.vtkXMLPPolyDataReader()
        if path.suffix == ".pvtp"
        else vtk.vtkXMLPolyDataReader()
    )
particle_reader.SetFileName(path)
particle_reader.Update()

data = particle_reader.GetOutput()
point_data = data.GetPointData()

for i in range(point_data.GetNumberOfArrays()):
    print(point_data.GetArrayName(i))

Then to get the actual data array, do something like this (with the array name you want, printed with the above code):

array = point_data.GetAbstractArray(name)