Skip to content

Add fast path to stack(::AbstractVectorOfArray) for numeric inner arrays #671

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
ChrisRackauckas merged 3 commits into from
Nov 2, 2026
Merged

Add fast path to stack(::AbstractVectorOfArray) for numeric inner arrays #671

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
63b1de6
Add fast path to stack(::AbstractVectorOfArray) for numeric inner arrays
ChrisRackauckas Oct 8, 2026
195c05a
Merge branch 'master' into voa-stack-fastpath
ChrisRackauckas Oct 16, 2026
8eceb31
Restrict stack fast path to inputs where it matches the general path
ChrisRackauckas Oct 16, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
8 changes: 8 additions & 0 deletions src/vector_of_array.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1045,6 +1045,14 @@ function Base.append!(
end

function Base.stack(VA::AbstractVectorOfArray; dims = :)
# Skipping the per-element `stack` is only valid where it returns an identical
# copy: it turns `BitArray`s into `Array{Bool}`, narrows abstract eltypes,
# and throws on 0-d and empty arrays.
ET = eltype(VA.u)
if ET <: Array{<:Number} && isconcretetype(ET) && isconcretetype(eltype(ET)) &&
ndims(ET) >= 1 && !any(isempty, VA.u)
return stack(VA.u; dims)
end
return stack(stack.(VA.u); dims)
end

Expand Down
16 changes: 16 additions & 0 deletions test/Core/interface_tests.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -208,6 +208,22 @@ testva = VA[VA[ones(2, 2), 2ones(2, 2)], 3ones(2, 2, 2)]
@test stack(testva) ==
[1.0 1.0; 1.0 1.0;;; 2.0 2.0; 2.0 2.0;;;; 3.0 3.0; 3.0 3.0;;; 3.0 3.0; 3.0 3.0]

numeric_stack = VectorOfArray([rand(2) for _ in 1:1000])
stack(numeric_stack) # compile away type instability before measuring
@test (@allocated stack(numeric_stack)) < 20_000 # final 2x1000 Float64 array alone is 16000 bytes
@test stack(numeric_stack) == reduce(hcat, numeric_stack.u)

stack_inputs = (
[rand(3) for _ in 1:2], [rand(2, 2) for _ in 1:3], [[1, 2], [3, 4]],
Vector{Real}[[1, 2.0], [3, 4.0]], [trues(3), falses(3)], [trues(2, 2), falses(2, 2)],
)
for u in stack_inputs, dims in (:, 1, 2)
@test typeof(stack(VectorOfArray(u); dims)) == typeof(stack(stack.(u); dims))
@test stack(VectorOfArray(u); dims) == stack(stack.(u); dims)
end
@test_throws BoundsError stack(VectorOfArray([fill(1.0), fill(2.0)]))
@test_throws ArgumentError stack(VectorOfArray([Float64[], Float64[]]))

# convert array from VectorOfArray/DiffEqArray
t = 1:8
recs = [rand(10, 7) for i in 1:8]
Expand Down
Loading