Extracting subdomain data for each node

General
1

I have a mesh with 2 subdomains - dx(0) and dx(1) . I wanted the know the subdomain data for each node.

I have got the nodal values of function w (determined by solve(a==L,w,bc) ) using w.compute_vertex_values(mesh).

#Do we have similar command to compute subdomain data for each node, like list of dx(0) or dx(1) for each node.

I tried using a0= np.ndarray[np.float64[0.09333333, 0. ]]

SubDomain.inside(a0, True) 

TypeError                                 Traceback (most recent call last)
/tmp/ipykernel_295/1734471881.py in <module>
----> 1 a0= np.ndarray[np.float64[0.09333333, 0.        ]]
      2 
      3 SubDomain.inside(a0, True)

TypeError: 'type' object is not subscriptable

but getting the following error.

The work is related to
https://comet-fenics.readthedocs.io/en/latest/demo/periodic_homog_elas/periodic_homog_elas.html
Any help is greatly appreciated!!!

2

To me it is not clear what you are trying to do in

as you have not presented a code that can repodue this.

Do you mean that you want the coordinates of all vertices within the cells marked with 0 or 1?

3

Hi@dokken

Thanks for your reply. I exactly want the coordinates of all vertices marked as 0 or 1 ( based on corresponding subdomain 0 or 1 respectively).

I will share other part of code too.

4

Consider the following MWE:

from IPython import embed
import dolfin


mesh = dolfin.UnitSquareMesh(10, 10)


class Left(dolfin.SubDomain):
    def inside(self, x, on_boundary):
        return x[0] < 0.5


cell_marker = dolfin.MeshFunction("size_t", mesh, mesh.topology().dim(), 0)
Left().mark(cell_marker, 1)

left_cells = cell_marker.where_equal(1)

cell_to_vertex = mesh.topology()(mesh.topology().dim(), 0)
x = mesh.coordinates()
for cell in left_cells:
    vertices = cell_to_vertex(cell)
    print(x[vertices])
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