Creating an iterative structure

General Usage
1

Given,

struct Point
    x::Float64
    y::Float64
    z::Float64
end
p1 = Point(1.0, 0.0, 0.0)
p2 = Point(1.0, 1.0, 0.0)
p3 = Point(1.0, 0.0, 1.0)

I want to define another iterative structure Points similar to Julia Array type which can store Point type objects p1, p2, p3. I am thinking, how to construct such an array so that Points[1], Points[2], Points[3] give me p1, p2, p3.

Thanks in advance :slight_smile:

2

Is Points = [p1 p2 p3] not sufficient for your usecase? What do you want to do with Points?

3

This gives Points of Vector type. I am asking, if there is any way to store objects similar to this [p1 p2 p3] but have a new user defined type.

4

You can define a type that is a subtype of arrays, but the question is what you want that structure to do that a vector of points does not?

By the way, take a look at StaticArrays, and the FieldVector super type, for defining your Points.

With FieldVector from StaticArrays you get define:

struct Point{T} <: FieldVector{3,T}
  x::T
  y::T
  z::T
end

And all the arithmetic works for Point.

1 Like
5

Well, what do you want to do with your hypothetical new Points type? Do you want to store a fixed number of points? An arbitrary number? What would a Points type to differently to a regular Vector?

If you just want to iterate over something and dispatch differently to Vector, you can define a simple wrapper type and implement the iterator interface for that type. If you want indexing, implement the indexing interface for that type (you’ll probably have to forward a bunch of methods to a wrapped Vector or Tuple).

FieldVector from StaticArrays is advanced usage - I’d encourage you to first familiarize yourself with how indexing and iteration works in julia and finding out how you want to use your new type before jumping into performance optimizations like StaticArrays.

2 Likes
6

For this particular use it actually helps a lot basic usage, because without it the user has to define it’s own basic arithmetic operators for summing, averaging, etc, the custom Points

7

They’re not asking about a single point though, they’re asking about a collection of points:

1 Like
8

Thanks @Sukera @lmiq .

1 Like
9

Yes, I know. I was just anticipating something.