On Tuesday, August 30, 2016 at 12:56:34 AM UTC, Miguel Goncalves wrote:
>
> There is a 2-year-old post
> <https://groups.google.com/forum/#!topic/julia-dev/goVB9Pp74H4> on
> julia-dev hinting at potential new syntax for removing columns from a 2D
> array. What is the current status on that?
>
> What is currently the most efficient way to remove a column or row from a
> 2D contiguous array?
>
For contiguous arrays ("Array" subtype of "DenseArray"), there seems it
will never be fast in the general case (edge case for last/first, might
allow for a view/subarry).
I looked into what you point to, and the issue is closed, but the solutions
here at least work:
http://stackoverflow.com/questions/17298586/how-to-delete-a-row-of-matrix-in-julia
I can't see that Julia couldn't be as fast as MATLAB, they chose however to
not do this by default, as it is slow (for big arrays).
[I guess sparse arrays, would also be not as slow.. depending..]
Maybe some other type <: DenseArray would help, could at least in theory,
be made (but I guess then other operations would have to be slower). I just
noticed:
https://github.com/KristofferC/BlockArrays.jl
that I do not know enough about yet.. It might be for other purposes..
--
Palli.
