Julia array tips
Convert vector of vector to matrix
Use the stack function.
stack([[1,0,1],[0,0,1]], dims=1) == [ 1 0 1 ; 0 0 1 ]
Convert linear index to 2D indices
Use CartesianIndices((nrow, ncol)) .
x = rand((7, 10))
CI = CartesianIndices((7, 10))
for i in 1:length(x)
r = CI[i][1]
c = CI[i][2]
@assert x[i] == x[r, c]
end