Returning a minimum index in an array in Julia

Question

I am converting some code from Matlab to Julia. In the matlab code:

[~,pStar] = min(min([dPlus,dMinus],[],2))

will return the minimum element in each row and output it in column form, then return the index (row) of the minimum element in the column just like:

>> M = [1,1,1;1,1,0;1,1,1]
M =
   1   1   1
   1   1   0
   1   1   1
>> min(M,[],2)
ans =
   1
   0
   1
>> [~,row] = min(min(M,[],2))
row =  2

My question is: what would be the Julia equivalent to this? Thank you

Answer 1

indmin returns the linear index of the minimum. You can convert that to subscript form by using ind2sub, and extract the row from that:

julia> indmin(M)
8

julia> row, col = ind2sub(M, indmin(M))
(2, 3)

julia> row
2

This approach avoids iterating twice and creating an intermediate array.

Update: In Julia >= 0.7, this has changed to argmin, returning a CartesianIndex which you can directly use. You can also use findmin to get both minimal value and its index.