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Fix union and union! of intervals #74

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Fix union and union! of intervals #74

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44 changes: 34 additions & 10 deletions src/interval.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -279,22 +279,24 @@ end

# There is power in a union.
"""
union(intervals::AbstractVector{<:AbstractInterval})
union(intervals::Union{AbstractInterval, AbstractVector{<:AbstractInterval}}, itrs...)

Flattens a vector of overlapping intervals into a new, smaller vector containing only
Flattens sets of overlapping intervals into a new, smaller vector containing only
non-overlapping intervals.
"""
function Base.union(intervals::AbstractVector{<:AbstractInterval})
return union!(convert(Vector{AbstractInterval}, intervals))
function Base.union(
interval::Union{AbstractInterval, AbstractVector{<:AbstractInterval}}, intervals...,
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Should we do:

Suggested change
interval::Union{AbstractInterval, AbstractVector{<:AbstractInterval}}, intervals...,
interval::Union{AbstractInterval, AbstractVector{<:AbstractInterval}}, intervals::Union{AbstractInterval, AbstractVector{<:AbstractInterval}}...,

Avoids a call such as union(Interval(1,2), 3) causing a confusing error

)
return union!(AbstractInterval[interval; intervals...])
end
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"""
union!(intervals::AbstractVector{<:Union{Interval, AbstractInterval}})
function Base.union!(intervals::AbstractVector{T}) where T <: AbstractInterval
if !(T <: Interval) && T != AbstractInterval
throw(ArgumentError(
"Cannot `union!` array of intervals of type $T as the type may change"
))
end
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@omus omus Jun 14, 2019 •
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It would be better to use dispatch here for future interval types can support their own union! methods

function Base.union!(intervals::AbstractVector{<:AbstractInterval})
    throw(ArgumentError("Cannot `union!` array of intervals of type $(eltype(intervals)) as the type may change"))
end

Base.union!(intervals::AbstractVector{<:Union{AbstractInterval,Interval}) = ...

(I think this works)

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Doesn't the existing definition already allow that?

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I think my point here was that this approach in the PR isn't the best for new interval types that want to define their own union! method.


Flattens a vector of overlapping intervals in-place to be a smaller vector containing only
non-overlapping intervals.
"""
function Base.union!(intervals::Union{AbstractVector{<:Interval}, AbstractVector{AbstractInterval}})
sort!(intervals)

i = 2
Expand All @@ -319,6 +321,28 @@ function Base.union!(intervals::Union{AbstractVector{<:Interval}, AbstractVector
return intervals
end

"""
union!(intervals::AbstractVector{<:Union{Interval, AbstractInterval}}, itrs...)

Flattens sets of overlapping intervals in-place into the first argument, making it a smaller
vector containing only non-overlapping intervals.
"""
function union!(
intervals::AbstractVector{<:AbstractInterval},
interval_varargs...
)
# imitates the behaviour of vcat/promote_eltypeof
for interval_vararg in interval_varargs
if interval_vararg isa AbstractInterval
push!(intervals, interval_vararg)
else
append!(intervals, interval_vararg)
end
end

return union!(intervals)
end

"""
superset(intervals::AbstractArray{<:AbstractInterval}) -> Interval

Expand Down
46 changes: 46 additions & 0 deletions test/interval.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -536,6 +536,18 @@
end

@testset "union" begin
a = Interval(-100, -1)
b = Interval(-3, 10)

@test union(a) == AbstractInterval[a]
@test union(b) == AbstractInterval[b]
@test union(a, b) == AbstractInterval[Interval(-100, 10)]
@test union(b, a) == AbstractInterval[Interval(-100, 10)]
@test union([a, b]) == AbstractInterval[Interval(-100, 10)]
@test union([b, a]) == AbstractInterval[Interval(-100, 10)]
@test union!([a, b]) == [Interval(-100, 10)]
@test union!([b, a]) == [Interval(-100, 10)]

intervals = [
Interval(-100, -1, Inclusivity(false, false)),
Interval(-10, -1, Inclusivity(false, false)),
Expand Down Expand Up @@ -572,5 +584,39 @@
Interval(-10, -1, Inclusivity(true, true))
]
@test union(intervals) == [Interval(-100, -1, Inclusivity(false, true))]

# anchored
intervals = [
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 12, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 12, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 13, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 13, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 14, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 14, 7, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 12, 8, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 12, 8, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 13, 8, tz"UTC"), Inclusivity(false, true)),
HourEnding{ZonedDateTime}(ZonedDateTime(2013, 2, 13, 8, tz"UTC"), Inclusivity(false, true)),
]

expected = [
Interval{ZonedDateTime}(ZonedDateTime(2013, 2, 12, 6, tz"UTC"), ZonedDateTime(2013, 2, 12, 8, tz"UTC"), Inclusivity(false, true)),
Interval{ZonedDateTime}(ZonedDateTime(2013, 2, 13, 6, tz"UTC"), ZonedDateTime(2013, 2, 13, 8, tz"UTC"), Inclusivity(false, true)),
Interval{ZonedDateTime}(ZonedDateTime(2013, 2, 14, 6, tz"UTC"), ZonedDateTime(2013, 2, 14, 7, tz"UTC"), Inclusivity(false, true)),
]

@test union(intervals) == expected
@test_throws ArgumentError union!(intervals)

abstract_intervals = convert(Vector{AbstractInterval}, intervals)
@test union(abstract_intervals) == expected
@test length(abstract_intervals) == length(intervals) # test that union doesn't mutate
@test union!(abstract_intervals) == expected
@test abstract_intervals == expected # test that union! does mutate

# varargs
@test union(intervals...) == expected
@test_throws MethodError union!(intervals...)
@test union!(abstract_intervals[1:1], abstract_intervals[2:3], abstract_intervals[4:end]...) == expected
end
end