Help: Remove one column of M*N array using index?

[Helen]

Does someone know how to remove one column by using index? 

Just as the in Matlab, you can use A[:,1]=[] to remove the first column or use  x[,-1] in R.

I don't want to use the way like A[:,[2,4:end]] to remove the third column.

Appreciate for the help!

[Tony Kelman]

This kind of question usually should go do julia-users instead of julia-dev, but it's a good question regardless.

There's some similar discussion here http://stackoverflow.com/questions/17298586/how-to-delete-a-row-of-matrix-in-julia

This is a bit more verbose than in Matlab (though the delete-and-copy behavior of Matlab is pretty slow), but appears to work:

A[:, 1:size(A,2) .!= 3]

-Tony

[Milan Bouchet-Valat]

For the sake of completeness, in the future you should be able to write something like

A[:, !3]

See https://github.com/JuliaLang/julia/issues/1032


Regards

[Kevin Squire]

Also for the sake of completeness: until you can write A[:, !3], A[:, 1:size(A,2) .!= 3] is going to make a copy of the array (which is what matlab does).  With large arrays, this is rather inefficient, which I think is one of the reasons it isn't easier in julia.

Cheers, Kevin