Sum elements of a struct

New to Julia
, ,
1

How can I sum the elements of MyStruct?

Code:

struct MyStruct
            a::Int 
            b::SVector{N_lds, Int64} 
            c::Int 
        end 

        import Base: -
        -(x::MyStruct, y::MyStruct) = MyStruct(x.a - y.a, x.b .- y.b, x.c - y.c)
        v1 = MyStruct(16, [0, 0, 1], 1)
        v2 = MyStruct(15, [5, 6, 1], 1)
        fg = v1 -v2
        
        sum(fg)

ERROR: MethodError: no method matching iterate(::MyStruct)

2

What do you want sum(MyStruct) to return?

v2 = MyStruct(15, [5, 6, 1], 1)

should it return 28?

3

No, the sum of the elements of fg. Should be -10.

4

I mean, should sum(v2) return 28?

5

yes

6

Okay, given that you know how to overload Base.-, it should be easy to write code to overwrite Base.sum.

But if you want sum to work automatically, you should write a method for iterate. If you were to count through the elements of MyStruct, would would that be a meaningful thing to do? In a mathematical sense. This is dependent on what MyStruct represents.

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7

Unless this is a toy example, this is probably not the recommended course of action and will come back to bite you in the future.

2 Likes
8

This seems like an XY problem. What are you actually trying to represent with your data structure here?

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