This works natively: a = Vector{Int}(undef, 2) a .= 2 However, this does not work, failing with a cryptic error: struct Foo x::Int end a = Vector{Foo}(undef, 2) a .= Foo(2) #= ERROR: MethodError: no method matching length(::Foo) Stacktrace: [1] _similar_for(::UnitRange{Int64}, ::Type, ::Foo,…

[image] BioTurboNick: Is there a reason not to provide for broadcasted assignment of custom types into an array of that type? Types default to be iterable-y and not scalar-y. So do something like: julia> a .= (Foo(2),) 2-element Array{Foo,1}: Foo(2) Foo(2) or define julia> Broadcast.broa…

Interesting, okay. Would it do any harm, or is it possible, to detect if length is defined for a type, and if not, treat it as scalar? (Thinking about whether it is worth suggesting a change to the language)

@kristoffer.carlsson , Your suggestion allows me to broadcast to an array range, but not to a single element of the array. a = Vector{Foo}(undef, 3) a[1:2] .= Foo(2) # works a[3] .= Foo(2) # error #= ERROR: MethodError: no method matching size(::Foo) Stacktrace: [1] axes at .\abstractarray.jl:75 …

Use = for that? It doesn’t work for other types either.

Ah, nevermind the deleted post, I thought it worked for numbers. Okay, so I need to check whether my array lookup will be one element or multiple elements and then have special cases for each? Seems like that shouldn’t be necessary. EDIT: Ah, so a[3:3] works okay but a[3] does not. That’s okay the…

I might be stating the obvious, but beware it’s one and the same object, which can lead to surprises if your objects are not fully immutable: julia> struct Foo x::Vector{Int} end julia> a = Vector{Foo}(undef, 2); julia> a .= (Foo([2]),) 2-element Array{Foo,1}: Foo([2]) Foo([2]) julia> push!(a[…

Btw, another way of creating a with identical objects is: julia> struct Foo x::Vector{Int} end julia> a = fill(Foo([2]), 2) 2-element Array{Foo,1}: Foo([2]) Foo([2]) (There’s also fill!.) In case you want unique objects, you can do: julia> a = 1:2 .|>_-> Foo([2]) 2-element Array{Foo,1}: Foo([…

@bennedich - Took me a moment to realize what you were saying, that only one object is created and then each array item points to it. Thank you, that’s good to remember.

Also, didn’t know Julia had the |> operator for function chaining, so thanks for showing me that.

Broadcasted assignment of custom types

General Usage

fredrikekre January 2, 2019, 4:19pm 4

See recent broadcast changes (iterate by default), scalar struct, and `@.` and linked issues/PRs.

Topic		Replies	Views
Error when assigning a struct, via broadcast, to an array of structs General Usage	2	552	September 7, 2020
No method matching length() for any dot syntax operation involving a struct New to Julia	6	1169	October 8, 2022
Making broadcast work for own type General Usage broadcast	4	1738	November 20, 2017
Broadcasting function over array of structs? New to Julia question	2	600	September 21, 2020
Fully lost with custom broadcasting interface General Usage broadcast , interface	3	1160	October 3, 2021

Broadcasted assignment of custom types

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