Hi all- I have a situation where I want to generate one of two types of arrays from a list comprehension. In the simplest case, all of the elements are Float64. This is straightforward and always works. In the other case, the elements are Union{Float64, Array{Float64,1}}. However, in practice, Juli…

I don’t think there is a way. This uses promote_typejoin internally. It has a special case for nothing and missing to give a small union, but for all other things, it will fall back to typejoin, which gets you either a concrete type or Any in all cases that I can think of. What benefit are you hopi…

Thanks for your reply. I was afraid that this might be the case. I have not ran a benchmark, but since it is a critical part of my code, I am following general advice to avoid abstract containers. My understanding is that a small union can mitigate this issue to some degree, but it’s still slower t…

[image] Christopher_Fisher: I have not ran a benchmark, but since it is a critical part of my code, I am following general advice to avoid abstract containers. Measuring what you are doing is at the very top of the general performance advice , above avoiding abstract containers. I highly recom…

You are right. I should have ran some benchmarks prior to opening the thread, but unfortunately, I cannot share the code, at least for now. So it may not have been that helpful. I did just run some tentative benchmarks, which suggest Any will probably cause performance issues in my larger code base…

How to avoid Any in list comprehensions with small unions

General Usage

Christopher_Fisher June 8, 2019, 9:56am 4

This might be useful for someone who comes across this post.

Topic		Replies	Views
Why doesn't `vect` return a union-typed result if the number of elements is small? Internals & Design performance , inference , type	3	636	September 13, 2022
Array of type Any vs Union General Usage question	5	3986	March 22, 2017
Type promotion: Why not use more unions? Internals & Design question	7	1448	February 2, 2018
Small union type failure General Usage	15	1264	April 15, 2021
Why are irregularly shaped arrays of arrays of type Any in Julia? New to Julia question	8	766	December 20, 2021

How to avoid Any in list comprehensions with small unions

Related topics