Skip to content

Define minimum and maximum of empty arrays to return typemax and typemin #52004

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

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Define minimum and maximum of empty arrays to return typemax and typemin #52004

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
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
Reland "add more methods and tests for reductions over empty arrays" 
Refs #29919
Refs #52003

This reverts commit 2a84214.
  • Loading branch information
@vtjnash
vtjnash committed Apr 16, 2024
commit 6ca85cd73f475d465885d29b3cd7a39a93953c8e
9 changes: 6 additions & 3 deletions base/reduce.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -338,7 +338,8 @@ reduce_empty(::typeof(*), ::Type{T}) where {T} = one(T)
reduce_empty(::typeof(*), ::Type{<:AbstractChar}) = ""
reduce_empty(::typeof(&), ::Type{Bool}) = true
reduce_empty(::typeof(|), ::Type{Bool}) = false

reduce_empty(::typeof(max), T) = typemin(T)
reduce_empty(::typeof(min), T) = typemax(T)
reduce_empty(::typeof(add_sum), ::Type{T}) where {T} = reduce_empty(+, T)
reduce_empty(::typeof(add_sum), ::Type{T}) where {T<:BitSignedSmall} = zero(Int)
reduce_empty(::typeof(add_sum), ::Type{T}) where {T<:BitUnsignedSmall} = zero(UInt)
Expand All @@ -362,8 +363,10 @@ mapreduce_empty(::typeof(identity), op, T) = reduce_empty(op, T)
mapreduce_empty(::typeof(abs), op, T) = abs(reduce_empty(op, T))
mapreduce_empty(::typeof(abs2), op, T) = abs2(reduce_empty(op, T))

mapreduce_empty(f::typeof(abs), ::typeof(max), T) = abs(zero(T))
mapreduce_empty(f::typeof(abs2), ::typeof(max), T) = abs2(zero(T))
mapreduce_empty(::typeof(abs), ::typeof(max), T) = abs(zero(T))
mapreduce_empty(::typeof(abs), ::typeof(min), T) = typemax(abs(zero(T)))
mapreduce_empty(::typeof(abs2), ::typeof(max), T) = abs2(zero(T))
mapreduce_empty(::typeof(abs2), ::typeof(min), T) = typemax(abs2(zero(T)))

# For backward compatibility:
mapreduce_empty_iter(f, op, itr, ItrEltype) =
Expand Down
23 changes: 21 additions & 2 deletions test/reduce.jl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -91,6 +91,10 @@ end
@test mapreduce(abs2, *, Float64[]) === 1.0
@test mapreduce(abs2, max, Float64[]) === 0.0
@test mapreduce(abs, max, Float64[]) === 0.0
@test mapreduce(abs2, min, Float64[]) === Inf
@test mapreduce(abs, min, Float64[]) === Inf
@test_throws ArgumentError mapreduce(abs2, &, Float64[])
@test_throws ArgumentError mapreduce(abs2, |, Float64[])
@test_throws "reducing over an empty collection is not allowed" mapreduce(abs2, &, Float64[])
@test_throws str -> !occursin("Closest candidates are", str) mapreduce(abs2, &, Float64[])
@test_throws "reducing over an empty collection is not allowed" mapreduce(abs2, |, Float64[])
Expand Down Expand Up @@ -246,8 +250,8 @@ prod2(itr) = invoke(prod, Tuple{Any}, itr)

# maximum & minimum & extrema

@test_throws "reducing over an empty" maximum(Int[])
@test_throws "reducing over an empty" minimum(Int[])
@test maximum(Int[]) === typemin(Int)
@test minimum(Int[]) === typemax(Int)
@test_throws "reducing over an empty" extrema(Int[])

@test maximum(Int[]; init=-1) == -1
Expand All @@ -258,6 +262,21 @@ prod2(itr) = invoke(prod, Tuple{Any}, itr)
@test minimum(sin, []; init=1) == 1
@test extrema(sin, []; init=(1, -1)) == (1, -1)

@test maximum(Float64[]) === -Inf
@test minimum(Float64[]) === +Inf

@test maximum(Float32[]) === -Inf32
@test minimum(Float32[]) === +Inf32

@test maximum(abs, Int[]) === 0
@test minimum(abs, Int[]) === typemax(Int)

@test maximum(abs, Float64[]) === 0.0
@test minimum(abs, Float64[]) === +Inf

@test maximum(abs, Float32[]) === 0.0f0
@test minimum(abs, Float32[]) === +Inf32

@test maximum(5) == 5
@test minimum(5) == 5
@test extrema(5) == (5, 5)
Expand Down