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Introduce in!(x, s::Set) to improve performance of unique() #45156

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merged 2 commits into from
May 3, 2022
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Introduce in!(x, s::Set) to improve performance of unique() #45156

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d3ff474
Introduce in!(x, s::Set) to improve performance of unique()
petvana May 2, 2022
709daeb
Comment on what in! does
petvana May 3, 2022
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41 changes: 17 additions & 24 deletions base/set.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,16 @@ end
isempty(s::Set) = isempty(s.dict)
length(s::Set) = length(s.dict)
in(x, s::Set) = haskey(s.dict, x)

# This avoids hashing and probing twice and it works the same as
# in!(x, s::Set) = in(x, s) ? true : (push!(s, x); false)
function in!(x, s::Set)
idx, sh = ht_keyindex2_shorthash!(s.dict, x)
idx > 0 && return true
_setindex!(s.dict, nothing, x, -idx, sh)
return false
end

push!(s::Set, x) = (s.dict[x] = nothing; s)
pop!(s::Set, x) = (pop!(s.dict, x); x)
pop!(s::Set, x, default) = (x in s ? pop!(s, x) : default)
Expand Down Expand Up @@ -137,10 +147,7 @@ function unique(itr)
out = Vector{T}()
seen = Set{T}()
for x in itr
if !in(x, seen)
push!(seen, x)
push!(out, x)
end
!in!(x, seen) && push!(out, x)
end
return out
end
Expand All @@ -164,16 +171,10 @@ _unique_from(itr, out, seen, i) = unique_from(itr, out, seen, i)
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
!in!(x, seenR) && push!(outR, x)
return _unique_from(itr, outR, seenR, i)
end
if !in(x, seen)
push!(seen, x)
push!(out, x)
end
!in!(x, seen) && push!(out, x)
end
return out
end
Expand All @@ -199,11 +200,7 @@ function unique(f, C; seen::Union{Nothing,Set}=nothing)
out = Vector{eltype(C)}()
if seen !== nothing
for x in C
y = f(x)
if y ∉ seen
push!(out, x)
push!(seen, y)
end
!in!(f(x), seen) && push!(out, x)
end
return out
end
Expand Down Expand Up @@ -401,23 +398,19 @@ false
```
"""
function allunique(C)
seen = Dict{eltype(C), Nothing}()
seen = Set{eltype(C)}()
x = iterate(C)
if haslength(C) && length(C) > 1000
for i in OneTo(1000)
v, s = x
idx, sh = ht_keyindex2_shorthash!(seen, v)
idx > 0 && return false
_setindex!(seen, nothing, v, -idx, sh)
in!(v, seen) && return false
x = iterate(C, s)
end
sizehint!(seen, length(C))
end
while x !== nothing
v, s = x
idx, sh = ht_keyindex2_shorthash!(seen, v)
idx > 0 && return false
_setindex!(seen, nothing, v, -idx, sh)
in!(v, seen) && return false
x = iterate(C, s)
end
return true
Expand Down