add two `Expression`s with a different number of components

Question

I have two Expressions, one with two components, another with three, e.g.,

e1 = Expression(('1.0', '2.0', '3.0'))
e2 = Expression(('1.0', '2.0'))

I would now like to add those two in such a way that

e_new[0] = e1[0] + e2[0]
e_new[1] = e1[1] + e2[1]
e_new[2] = e1[2]

What would be the appropriate way to do so?

Answer 1

e_new = e1 + as_vector((e2[0], e2[1], 0.0))

(not tested)