How to sort a vector by an expensive function in place efficiently?

General Usage Performance
10

Other than the StructArray trick, you could also try permute! to reduce allocations (or even Base.permute!!, as you don’t need to preserve the result of sortperm).

For example

sort_by!(f, v) = Base.permute!!(v, sortperm(f.(v)))

should reduce allocations. I’m not sure if it is slower or faster than simply v[sortperm(f.(v))] though.

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