Data projection from one mesh to another mesh

variational formulation
1

Hi, I have data for each quadrilateral cell in a mesh and I want to use the “RT” element. Is there any way to project the data from quadrilateral mesh to triangular mesh.

from dolfin import *
import numpy as np
# first mesh
mesh = RectangleMesh.create([Point(0,0), Point(1,1)], [4,4], CellType.Type.quadrilateral)
num_cell = mesh.num_cells()
V = FunctionSpace(mesh, "DG",0)
data = np.random.random(num_cell)     # dummy data
phi = Function(V)
phi.vector()[:] = data[:]

# another mesh
mesh2 = UnitSquareMesh(4,4)
V2 = FunctionSpace(mesh2, "DG",0)
phi2 = project(phi, V2) # Can we project something like that?

Thank you!
Ranjeet

2

For interpolation between non-matching meshes, see the LagrangeInterpolator.
You can Also consider the answers given at the old Q&A-site

3

Thank you so much for your advice. I finally able to interpolate data on two grids.