Taking cats seriously

[jonniedie]

• vcat of two ComponentVectors where they share any of the same component names should become a plain Array
• Need cat defined
• Faster cats, if possible

[jonniedie]

cc26c7f adds faster vcat and hcat reductions.

[jonniedie]

Apparently the first check box was already done some time ago.

[baggepinnen]

I'm wondering how to write generic code that concatenates ComponentMatrics. Consider concatenating two linear systems (source in ControlSystems: https://github.com/JuliaControl/ControlSystems.jl/blob/17e78c10ddaa8dbdff672af26eff313e65de904a/src/types/StateSpace.jl#L227)

    A = [s1.A                   zeros(T, nstates(s1), nstates(s2));
         zeros(T, nstates(s2), nstates(s1))        s2.A]

Here' the call to zeros produces a standard Array which loses the names of the states if s1.A and s2.A are ComponentArrays. Ideally, methods should be written completely generically, i.e., without knowing about ComponentArrays, but still propagate the correct type information. I.e., it would be nice if all operations +,-,*,/ between linear systems could be generically written and used with ComponentArrays to keep track of the names of states.

[baggepinnen]

vcat and hcat do not seem to work for CompoenentMatrix, only for ComponentVector

[jonniedie]

I'll try to get to this one tonight. It's going to take a little work.

[jonniedie]

@baggepinnen I think 04387cf should do the trick. Let me know if you run into any bugs with it. I tried to cover as much as I could with the tests, but there are a lot of ways to bugs to get in here.

[jonniedie]

Ugh, nevermind. This broke something on Julia versions <= v1.4. I'll have to dig into that.