> > > This 3 column are neccessary for later analysis in my work, first and > second column index and 3rd values. I have to use three columns same time. >
Ok right so, whatever the exact expression is, it's going to have the form f(A[:,1:2]) where f does some indexing function followed sometime later by g(A[:,3]) where g does some value stuff. but you don't have h(A[:,1:3]) because there's no builtin thing that does both indexing and evaluation simultaneously I'm using f g and h just to short-hand describe what's going on, not to imply they are actually called f, g, h or even that they're actually formally functions. So if that's the case then really why not use A and B? Convenience, Encapsulation? Sure, that's valid but I'm suggesting that those two things are even better served by using composites, because then you have the type system working for you instead of against you.
