For performance reasons, I want to replace usage of standard arrays with StaticArrays. However, I couldn’t find how to initialize an empty StaticArray of a given size, that I can populate as values become available. I am looking for something equivalent of: Array{Int64}(undef, 10) but for StaticAr…

The length of a static array is part of its type. Thus, passing len as an Int results in dynamic dispatches: the only thing known at compile time is that len is an Int. If you instead pass it as a ::Val{len}, that is an object of type Val{len}, then the value is known at compile time. julia> funct…

since staticarray is static, if you created an empty one, you couldn’t ever put stuff in it.

I see. But you still could replace it in nested container;)

Static arrays are like numbers. You cannot create an empty number, and if you have a vector of numbers, when you want to change a value you replace the number at a position in the vector by another number. The same goes for static arrays. They are not mutable, you have to create them with values an…

Thank you for the explanation. I misunderstood them. I thought that there size could not be changed, however, the values in them could be changed. For example, the following code works, and does not throw any errors. function arr3(len) a = Array{Int}(undef, len) a = StaticArrays.SizedVector{len}(…

Oh yes, StaticArrays also provides mutable, statically sized arrays. For those the explanation above does not apply. (But the performance is not the same either). The interface for mutable, statically sized, arrays in StaticArrays is the MArray. (I never saw the use of that constructor you used the…

That’s the kind of example I love: using a dynamic array to initialize a possibly static array;)

Thank you! For these statically sized arrays, is the performance better than the regular arrays? And, if yes, can these by initialized with undef or something similar? The constructor I used is documented here: https://juliaarrays.github.io/StaticArrays.jl/stable/pages/api/#StaticArrays.SizedArray …

I am not suggesting that that is a good way :slight_smile: But I did try to see if that helped over just using the dynamic array, and it did not. It made performance much worse. Hence, my question.

julia> using StaticArrays julia> MVector{10,Float64}(undef) 10-element MVector{10, Float64} with indices SOneTo(10): 4.4e-323 6.9288606158516e-310 6.92886061148325e-310 0.0 6.9288606158516e-310 6.92886061148325e-310 0.0 6.9288606158516e-310 6.9288723779309e-310 0.0

How to initialize an empty StaticArray?

General Usage

goerch October 17, 2021, 7:51pm 2

Theoretically yes, as I learned from Create a struct with uninitialized fields. But practically: I don’t know.

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How to initialize an empty StaticArray?

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