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Implement accumulate and friends for Tuple #34654

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merged 4 commits into from
Feb 26, 2020
Merged

Implement accumulate and friends for Tuple #34654

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4b7dc0c
Implement `accumulate` and friends for Tuple
tkf Feb 4, 2020
8da5715
Add NEWS
tkf Feb 4, 2020
d52bf3f
Merge branch 'master' into accumulate-tuple
tkf Feb 26, 2020
039196f
Directly call Base.afoldl to be slightly more compiler-friendly
tkf Feb 26, 2020
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31 changes: 27 additions & 4 deletions base/accumulate.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -92,12 +92,15 @@ function cumsum(A::AbstractArray{T}; dims::Integer) where T
end

"""
cumsum(x::AbstractVector)
cumsum(itr::Union{AbstractVector,Tuple})

Cumulative sum a vector. See also [`cumsum!`](@ref)
Cumulative sum an iterator. See also [`cumsum!`](@ref)
to use a preallocated output array, both for performance and to control the precision of the
output (e.g. to avoid overflow).

!!! compat "Julia 1.5"
`cumsum` on a tuple requires at least Julia 1.5.

# Examples
```jldoctest
julia> cumsum([1, 1, 1])
Expand All @@ -111,9 +114,13 @@ julia> cumsum([fill(1, 2) for i in 1:3])
[1, 1]
[2, 2]
[3, 3]

julia> cumsum((1, 1, 1))
(1, 2, 3)
```
"""
cumsum(x::AbstractVector) = cumsum(x, dims=1)
cumsum(itr) = accumulate(add_sum, itr)


"""
Expand Down Expand Up @@ -163,12 +170,15 @@ function cumprod(A::AbstractArray; dims::Integer)
end

"""
cumprod(x::AbstractVector)
cumprod(itr::Union{AbstractVector,Tuple})

Cumulative product of a vector. See also
Cumulative product of an iterator. See also
[`cumprod!`](@ref) to use a preallocated output array, both for performance and
to control the precision of the output (e.g. to avoid overflow).

!!! compat "Julia 1.5"
`cumprod` on a tuple requires at least Julia 1.5.

# Examples
```jldoctest
julia> cumprod(fill(1//2, 3))
Expand All @@ -182,9 +192,13 @@ julia> cumprod([fill(1//3, 2, 2) for i in 1:3])
[1//3 1//3; 1//3 1//3]
[2//9 2//9; 2//9 2//9]
[4//27 4//27; 4//27 4//27]

julia> cumprod((1, 2, 1))
(1, 2, 2)
```
"""
cumprod(x::AbstractVector) = cumprod(x, dims=1)
cumprod(itr) = accumulate(mul_prod, itr)


"""
Expand Down Expand Up @@ -247,6 +261,15 @@ function accumulate(op, A; dims::Union{Nothing,Integer}=nothing, kw...)
accumulate!(op, out, A; dims=dims, kw...)
end

function accumulate(op, xs::Tuple; init = _InitialValue())
rf = BottomRF(op)
ys, = foldl(xs; init = ((), init)) do (ys, acc), x
acc = rf(acc, x)
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Note: this uses the machinery I added in #33526

julia/base/reduce.jl

Lines 73 to 78 in 3720edf

struct BottomRF{T}
rf::T
end
@inline (op::BottomRF)(::_InitialValue, x) = reduce_first(op.rf, x)
@inline (op::BottomRF)(acc, x) = op.rf(acc, x)

(ys..., acc), acc
end
return ys
end
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Does this implementation lead to unrolled code?

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It const-folds, as shown in the OP. It is also unrolled when the tuple is not constant:

julia> @code_typed optimize=true cumsum(ntuple(identity, 10))
CodeInfo(
1 ── %1  = (getfield)(itr, 1)::Int64
│    %2  = (getfield)(itr, 2)::Int64
│    %3  = (getfield)(itr, 3)::Int64
│    %4  = (getfield)(itr, 4)::Int64
│    %5  = (getfield)(itr, 5)::Int64
│    %6  = (getfield)(itr, 6)::Int64
│    %7  = (getfield)(itr, 7)::Int64
│    %8  = (getfield)(itr, 8)::Int64
│    %9  = (getfield)(itr, 9)::Int64
│    %10 = (getfield)(itr, 10)::Int64
│    %11 = Base.add_int(%1, %2)::Int64
│    %12 = Base.add_int(%11, %3)::Int64
│    %13 = Base.add_int(%12, %4)::Int64
│    %14 = Base.add_int(%13, %5)::Int64
│    %15 = Base.add_int(%14, %6)::Int64
│    %16 = Base.add_int(%15, %7)::Int64
│    %17 = Base.add_int(%16, %8)::Int64
│    %18 = Base.add_int(%17, %9)::Int64
│    %19 = Base.add_int(%18, %10)::Int64
│    %20 = Core.tuple(%1, %11, %12, %13, %14, %15, %16, %17, %18, %19)::NTuple{10,Int64}
└───       goto #3
2 ──       $(Expr(:meta, :nkw, 1))
3 ┄─       goto #4
4 ──       goto #6
5 ──       $(Expr(:meta, :nkw, 1))
6 ┄─       goto #7
7 ──       goto #9
8 ──       $(Expr(:meta, :nkw, 1))
9 ┄─       goto #10
10 ─       return %20
) => NTuple{10,Int64}


"""
accumulate!(op, B, A; [dims], [init])

Expand Down
11 changes: 11 additions & 0 deletions test/tuple.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,17 @@ end
end
end

@testset "accumulate" begin
@test @inferred(cumsum(())) == ()
@test @inferred(cumsum((1, 2, 3))) == (1, 3, 6)
@test @inferred(cumprod((1, 2, 3))) == (1, 2, 6)
@test @inferred(accumulate(+, (1, 2, 3); init=10)) == (11, 13, 16)
op(::Nothing, ::Any) = missing
op(::Missing, ::Any) = nothing
@test @inferred(accumulate(op, (1, 2, 3, 4); init = nothing)) ===
(missing, nothing, missing, nothing)
end

@testset "ntuple" begin
nttest1(x::NTuple{n, Int}) where {n} = n
@test nttest1(()) == 0
Expand Down