CODEWITHSUNDEEP
julia
Kilian K.
Kilian K.

Reputation: 21

How do I perform a nested iteration?

I defined a function m(r,T,a,w) and I have vectors for the variables r,T,w. What I want to do is to take the first element of each of those vectors and iterate my function for a in 1:T, then take the sum and repeat this iteration for the second element of those vectors and so on. In the end I want to have a vector consisting of all the sums. I would appreciate your help.

What I tried so far:

(W,R,LE are the vectors for the variables for w,r,T, respectively)

M = []
for w in W, r in R, T in LE 
    for a in 1:T
    MM=sum(m(r,T,a,w))
    push!(M,MM)
end
end

clearly Julia would not recognise what Im trying to do

Upvotes: 1

Views: 129

Answers (3)

Kilian K.
Kilian K.

Reputation: 21

Thanks for the very helpful comments. I managed to code what I wanted

  MM = Vector{Float64}()
    M = Vector{Float64}()
    for (w, r, T) in zip(W, R, LE)
        for a in 1:T
          push!(MM, m(r,T,a,w))
        end
          push!(M,sum(MM))
    end

Upvotes: 0

Scott Jones
Scott Jones

Reputation: 1750

Matt's answer is correct, but you might want to improve a few other things, such as the types, and putting this in a function so that it isn't using a global variable. Do you know what the type of the sum is? Would a Float64 work, or a Int64? For example:

function myfun(W, R, LE)
    M = Vector{Float64}()
    for (w, r, T) in zip(W, R, LE), a in T
        push!(M, sum(m(r, T, a, w)))
    end
    M
end

Upvotes: 0

mbauman
mbauman

Reputation: 31342

The syntax:

for w in W, r in R, T in LE
    ...

does not iterate over the vectors at the same time. Rather, it is equivalent to the product:

for w in W
    for r in R
        for T in LE
            ...

It sounds like you want to iterate over those three vectors at the same time. In that case, you can use zip:

for (w,r,T) in zip(W,R,LE)
    ...

Upvotes: 4

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