Add point data to mesh and save as vtu
Question:
I am trying to add more properties to a *vtu file using pyvista. I have written a python code which generates 9 columns of data for all the points in the mesh. I want to add them to the existing *vtu file. I found add_field_data, but I want to add as point data, not field data or cell data.
I also considered converting the point data in the original *vtu file to a numpy array and concatenating them, but I do not know how to save this numpy array as a *vtu file.
Any help in any of the 2 directions is highly appreciated, although I would prefer the former.
Thanks in advance,
Answers:
It’s not clear to me why we have add_field_data() and no add_point_data() or add_cell_data(), but you can always use the point_data/cell_data/field_data attributes of mesh types, see for instance this tutorial page.
If you already have a mesh and a 1d array of scalars scalars of shape (mesh.n_points,) (or a 2d array with shape (mesh.n_points, d), actually) then all you need to do with your mesh is
mesh.point_data['name of your point data comes here'] = scalars
You’ll get an error in case the shape of scalars is invalid. You can then just
- read the
.vtu file with something like mesh = pv.read('name_of_your_file.vtu')
- add the scalars as above
- call
mesh.plot() or something more complicated to make sure the scalars look the way you expect them to (optional but recommended)
- call
mesh.save('output_file_name.vtu')
If you plot your mesh with your 9-component scalars of shape (n_points, 9) you’ll probably want to choose a single component (a single column) to plot by. You can do this with
mesh.plot(scalars='name of your point data comes here', component=3)
to pick out column index 3.
I am trying to add more properties to a *vtu file using pyvista. I have written a python code which generates 9 columns of data for all the points in the mesh. I want to add them to the existing *vtu file. I found add_field_data, but I want to add as point data, not field data or cell data.
I also considered converting the point data in the original *vtu file to a numpy array and concatenating them, but I do not know how to save this numpy array as a *vtu file.
Any help in any of the 2 directions is highly appreciated, although I would prefer the former.
Thanks in advance,
It’s not clear to me why we have add_field_data() and no add_point_data() or add_cell_data(), but you can always use the point_data/cell_data/field_data attributes of mesh types, see for instance this tutorial page.
If you already have a mesh and a 1d array of scalars scalars of shape (mesh.n_points,) (or a 2d array with shape (mesh.n_points, d), actually) then all you need to do with your mesh is
mesh.point_data['name of your point data comes here'] = scalars
You’ll get an error in case the shape of scalars is invalid. You can then just
- read the
.vtufile with something likemesh = pv.read('name_of_your_file.vtu') - add the scalars as above
- call
mesh.plot()or something more complicated to make sure the scalars look the way you expect them to (optional but recommended) - call
mesh.save('output_file_name.vtu')
If you plot your mesh with your 9-component scalars of shape (n_points, 9) you’ll probably want to choose a single component (a single column) to plot by. You can do this with
mesh.plot(scalars='name of your point data comes here', component=3)
to pick out column index 3.