[firedrake] Mapping nodal values from parent to extruded mesh

[Tuomas Karna]

Hi all,

I'd need to copy nodal values between fields on parent and extruded 
meshes. For example, copy 2d->3d (constant over vertical) or 3d->2d 
(extract surface/bottom level). The horizontal function space is the 
same. Is there an easy way to do this? Is there a map of extruded nodes 
somewhere?

Thanks,

Tuomas