How To Extract A Plane From A 3D Variable In FiPy (3D To 2D)

I have a variable on a 3D mesh and I am trying to cut a plan. I am surprised this question hasn't been asked before, it looks an easy and common problem but I haven't found any goo

Solution 1:

The cell centers are located at z=0.5, 1.5, 2.5, ... so FiPy is doing it's best to find the nearest cells to z=0, 1, 2, ...

Try

var2D.setValue(var3D((x2D, y2D, 
                      zcut * ones(var2D.mesh.numberOfCells) + dx/2.), order=0))