plotting Waveguide mode components about femwell

[lukasc-ubc]

It would also be nice to be able to get an object returned from the .show() method, namely the fig and ax, so we can edit, and change the axis limits for example.

Here is some code that generated what I am looking for:

# Plot Real(Ex) field
fig, ax = plt.subplots()
mode = modes[0]
basis = mode.basis
from skfem import ElementVector; ElementDG; ElementTriP1
(et, et_basis), (ez, ez_basis) = basis.split(mode.E.real)
plot_basis = et_basis.with_element(ElementVector(ElementDG(ElementTriP1())))
et_xy = plot_basis.project(et_basis.interpolate(et))
(et_x, et_x_basis), (et_y, et_y_basis) = plot_basis.split(et_xy)
plt.title("Electric field, x component")
plt.axis([-core_width*2, core_width*2, -core_thickness*2, core_thickness*3])
plt.xlabel('Width [microns]')
plt.ylabel('Thickness direction [microns]')
for subdomain in basis.mesh.subdomains.keys() - {"gmsh:bounding_entities"}:
    basis.mesh.restrict(subdomain).draw(ax=ax, boundaries_only=True, color="k", linewidth=3)
et_x_basis.plot(et_x, ax=ax, shading="gouraud", colorbar=True)

[HelgeGehring]

Looks great, thanks!
Adding a parameter sounds like a great enhancement!

maybe something like `plot_mode(...., components="xy"), where one can just submit one letter to have one field as well as a arbitary combination?