Is there Julia equivalent for Matlab's “logical” matrix which you can use to mark certain positions in matrix and then use it for matrix manipulation?
In matlab it looks like this:
A=magic(3);
C=eye(size(A));
C=logical(C);
M=A;
M(C)=0;
I need to keep zeros on main diagonal. In matlab I would do it like this, but in Julia there is no "logical" matrix. I searched for Julia equivalent but i couldn't find anything. Thanks in advance!
You can create a BitArray or an Array of Bools, which are for most intents and purposes the same.
E.g.
> using LinearAlgebra
>I(3) # `I()` is the identity matrix function
3×3 Diagonal{Bool,Array{Bool,1}}:
1 ⋅ ⋅
⋅ 1 ⋅
⋅ ⋅ 1
And you can use it to zero out elements in another matrix by broadcasting the logical not operator ~, and then multiplying each element in the other matrix (by broadcasting * with .*).
For example:
> x = reshape(1:9,3,3)
1 4 7
2 5 8
3 6 9
> x .* .~I(3)
0 4 7
2 0 8
3 6 0