Help with two Julia lines of code whose syntax is unclear to me

New to Julia
3

To further explain the motivation for the above code, findmax returns a tuple of (maximum value, index), and the .- (0, 1) part is used to subtract 1 from the index but leave the value unchanged, i.e. change the index from 1-based to 0-based:

julia> r = rand(3)
3-element Array{Float64,1}:
 0.43522862419490305
 0.7670653549580913
 0.4966565072349449

julia> findmax(r)
(0.7670653549580913, 2)

julia> findmax(r) .- (0, 1)
(0.7670653549580913, 1)

I agree with you that it’s not exactly obvious at first sight. A clearer way of writing the same thing would be:

julia> maxval, maxidx = findmax(r)
(0.7670653549580913, 2)

julia> (maxval, maxidx - 1)
(0.7670653549580913, 1)

In your second line, [2] chooses the index only, and -1 changes it to be 0-based.

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