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RFC: Implement unique consistently #29038

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RFC: Implement unique consistently #29038

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217 changes: 113 additions & 104 deletions base/set.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -89,46 +89,7 @@ julia> unique(Real[1, 1.0, 2])
2
```
"""
function unique(itr)
T = @default_eltype(itr)
out = Vector{T}()
seen = Set{T}()
y = iterate(itr)
y === nothing && return out
x, i = y
if !isconcretetype(T) && IteratorEltype(itr) == EltypeUnknown()
S = typeof(x)
return _unique_from(itr, S[x], Set{S}((x,)), i)
end
push!(seen, x)
push!(out, x)
return unique_from(itr, out, seen, i)
end

_unique_from(itr, out, seen, i) = unique_from(itr, out, seen, i)
@inline function unique_from(itr, out::Vector{T}, seen, i) where T
while true
y = iterate(itr, i)
y === nothing && break
x, i = y
S = typeof(x)
if !(S === T || S <: T)
R = promote_typejoin(S, T)
seenR = convert(Set{R}, seen)
outR = convert(Vector{R}, out)
if !in(x, seenR)
push!(seenR, x)
push!(outR, x)
end
return _unique_from(itr, outR, seenR, i)
end
if !in(x, seen)
push!(seen, x)
push!(out, x)
end
end
return out
end
unique(itr) = _unique(itr)

"""
unique(f, itr)
Expand All @@ -145,57 +106,7 @@ julia> unique(x -> x^2, [1, -1, 3, -3, 4])
4
```
"""
function unique(f::Callable, C)
out = Vector{eltype(C)}()
seen = Set()
for x in C
y = f(x)
if !in(y, seen)
push!(seen, y)
push!(out, x)
end
end
out
end

# If A is not grouped, then we will need to keep track of all of the elements that we have
# seen so far.
function _unique!(A::AbstractVector)
seen = Set{eltype(A)}()
idxs = eachindex(A)
y = iterate(idxs)
count = 0
for x in A
if x ∉ seen
push!(seen, x)
count += 1
A[y[1]] = x
y = iterate(idxs, y[2])
end
end
resize!(A, count)
end

# If A is grouped, so that each unique element is in a contiguous group, then we only
# need to keep track of one element at a time. We replace the elements of A with the
# unique elements that we see in the order that we see them. Once we have iterated
# through A, we resize A based on the number of unique elements that we see.
function _groupedunique!(A::AbstractVector)
isempty(A) && return A
idxs = eachindex(A)
y = first(A)
# We always keep the first element
it = iterate(idxs, iterate(idxs)[2])
count = 1
for x in Iterators.drop(A, 1)
if !isequal(x, y)
y = A[it[1]] = x
count += 1
it = iterate(idxs, it[2])
end
end
resize!(A, count)
end
unique(f::Callable, itr) = _unique(itr, f)

"""
unique!(A::AbstractVector)
Expand Down Expand Up @@ -231,26 +142,124 @@ julia> unique!(B)
42
```
"""
function unique!(A::Union{AbstractVector{<:Real}, AbstractVector{<:AbstractString},
AbstractVector{<:Symbol}})
if isempty(A)
return A
elseif issorted(A) || issorted(A, rev=true)
return _groupedunique!(A)
unique!(A::AbstractVector) = _unique!(A, nothing, false)

# issorted fails for some element types, so the method above has to be restricted to
# elements with isless/< defined. "hasmethod(isless,...)" is too slow for this purpose.
unique!(A::AbstractVector{<:Union{Real,AbstractString,Symbol}}) =
_unique!(A, nothing, issorted(A) || issorted(A, rev = true))


"""
unique!(f, A::AbstractVector)

Modifies the array `A` to contain one value from `A` for each unique value produced by `f`
applied to elements of `A`.

# Examples
```jldoctest
julia> unique!(x -> x^2, [1, -1, 3, -3, 4])
3-element Array{Int64,1}:
1
3
4
```
"""
unique!(f::Callable, A::AbstractVector) = _unique!(A, f, false)

# Two concrete types for inplace and out of place unique algorithms
abstract type Uniquifier end
struct UO{I,T,S} <: Uniquifier itr::I; out::Vector{T}; seen::Set{S}; end
struct UI{I,S} <: Uniquifier itr::I; seen::Set{S}; i::Vector{Int}; end
struct UOF{I,T,S,F <: Callable} <: Uniquifier itr::I; out::Vector{T}; seen::Set{S}; f::F; end
struct UIF{I,S,F <: Callable} <: Uniquifier itr::I; seen::Set{S}; i::Vector{Int}; f::F; end

# Implementation bodies for unique and unique!
function _unique(itr, f::Union{Nothing, Callable} = nothing)
T = @default_eltype(itr)
y = iterate(itr)
y === nothing && return T[]
x, st = y
R = !isconcretetype(T) && IteratorEltype(itr) == EltypeUnknown() ? typeof(x) : T
if f !== nothing
fx = f(x)
return __uniquify(UOF(itr, R[], Set{typeof(fx)}(), f), st, x, fx)
else
return _unique!(A)
return __uniquify(UO(itr, R[], Set{R}()), st, x)
end
end
# issorted fails for some element types, so the method above has to be restricted to
# elements with isless/< defined.
function unique!(A)
if isempty(A)
return A

function _unique!(A::AbstractVector, f::Union{Callable, Nothing}, sorted::Bool)
isempty(A) && return A
sorted && return _uniquify_sorted(A)
x, st = iterate(A)
if f !== nothing
fx = f(x)
return __uniquify(UIF(A, Set{typeof(fx)}(), [firstindex(A)], f), st, x, fx)
else
return _unique!(A)
return __uniquify(UI(A, Set{typeof(x)}(), [firstindex(A)]), st, x)
end
end

# Generic implementations of unique/unique! with and without function application
__uniquify(u, st, x, fx = nothing) = _uniquify(u, st, x, fx)
@inline function _uniquify(u::T, st, x, fx = nothing) where {T<:Uniquifier}
_register(u, x, fx)
y = iterate(u.itr, st)
while y !== nothing
x, st = y
fx = _element(u, x)
_fits(u, x, fx) || return __uniquify(_recreate(u, x, fx), st, x, fx)
_register(u, x, fx)
y = iterate(u.itr, st)
end
return _finish(u)
end

# Specififc implementation for sorted data with inplace update
function _uniquify_sorted(A::AbstractVector)
i = firstindex(A) + 1
a = iterate(A)
lx, st = a
while a !== nothing
x, st = a
isequal(lx, x) || (lx = A[i] = x; i += 1)
a = iterate(A, st)
end
resize!(A, i - firstindex(A))
end

@inline _element(u::Union{UOF,UIF}, x) = u.f(x)
@inline _element(::Union{UO,UI}, ::Any) = nothing

# checks if the value has been dealt with before and process it otherwise
@inline _register(u::UO, x, ::Nothing) = !in(x, u.seen) && (push!(u.seen, x); push!(u.out, x))
@inline _register(u::UI, x, ::Nothing) = !in(x, u.seen) && (push!(u.seen, x); u.itr[u.i[1]] = x; u.i[1] += 1)
@inline _register(u::UOF, x, fx) = !in(fx, u.seen) && (push!(u.seen, fx); push!(u.out, x))
@inline _register(u::UIF, x, fx) = !in(fx, u.seen) && (push!(u.seen, fx); u.itr[u.i[1]] = x; u.i[1] += 1)

# Does the current values fit in the data structures?
@inline _fits(u::UOF{I,T,S}, x, fx) where {I,T,S} = x isa T && fx isa S
@inline _fits(u::UIF{I,S}, x, fx) where {I,S} = fx isa S
@inline _fits(u::UO{I,T,S}, x, ::Nothing) where {I,T,S} = x isa T
@inline _fits(u::UI{I,S}, x, ::Nothing) where {I,S} = x isa S

# Recreates the data structures with adjusted types
_recreate(u::UOF, x, fx) = UOF(u.itr, _adjust(u.out, x), _adjust(u.seen, fx), u.f)
_recreate(u::UIF, x, fx) = UIF(u.itr, _adjust(u.seen, fx), u.i, u.f)
_recreate(u::UO, x, ::Nothing) = UO(u.itr, _adjust(u.out, x), _adjust(u.seen, x))
_recreate(u::UI, x, ::Nothing) = UI(u.itr, _adjust(u.seen, x), u.i)
# if an unfitting element type appears, adjust the data structures
# make sure the 'out' array always fits the element
# if the 'seen' set has to deal abstract type switch to Any
_adjust(out::Vector{T}, ::U) where {T,U} = convert(Vector{promote_typejoin(T,U)}, out)
_adjust(seen::Set{T}, ::U) where {T,U} = convert(Set{T === U ? T : Any}, seen)

# return of uniquify functions depends on inplace/out of place
_finish(u::Union{UO,UOF}) = u.out
_finish(u::Union{UI,UIF}) = resize!(u.itr, u.i[1] - firstindex(u.itr))


"""
allunique(itr) -> Bool

Expand Down
22 changes: 22 additions & 0 deletions test/sets.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -381,6 +381,28 @@ end
u = [1,2,5,1,3,2]
end

@testset "unique(!) types" begin
@test @inferred(unique!(collect(1:1))) == [1]
@test unique(Real[1., 1])::Vector{Real} == unique!(Real[1., 1])::Vector{Real} == [1.]
@test unique(Real[1, 1.])::Vector{Real} == unique!(Real[1, 1.])::Vector{Real} == [1]
for t in [Int, Integer, Any]
a = t[1,-1, 1, -1]
g = (x for x in a)
@test unique(abs,a)::typeof(a) == unique!(abs, copy(a))::typeof(a) == [1]
@test unique(a)::typeof(a) == unique!(copy(a))::typeof(a) == [1,-1]
@test unique(abs, g)::Vector{Int} == [1]
@test unique(g)::Vector{Int} == [1,-1]
end
end

@testset "unique!(f)" begin
a = [5, 1, 8, 9, 3, 4, 10, 7, 2, 6]
b = copy(a)
@test unique!(iseven, a) === a == [5, 8]
@test unique!(n -> n % 3, b) === b == [5, 1, 9]
@test unique!(n -> n % 3, Int[]) == Int[]
end

@testset "allunique" begin
@test allunique([])
@test allunique(Set())
Expand Down