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Add handling of an empty iterator for mean and var #29033

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merged 5 commits into from
Oct 11, 2018
Merged

Add handling of an empty iterator for mean and var #29033

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4f9028c
add handling of an empty iterator for mean and var
bkamins Sep 4, 2018
40b2ea7
additional tests
bkamins Sep 4, 2018
9e0b0ba
further cleanup of tests
bkamins Sep 4, 2018
0487d17
change to oftype and define mean of empty range
bkamins Sep 14, 2018
bff28ee
remove module qualifier
bkamins Sep 14, 2018
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8 changes: 4 additions & 4 deletions stdlib/Statistics/src/Statistics.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -131,8 +131,8 @@ mean(A::AbstractArray; dims=:) = _mean(A, dims)
_mean(A::AbstractArray{T}, region) where {T} = mean!(Base.reducedim_init(t -> t/2, +, A, region), A)
_mean(A::AbstractArray, ::Colon) = sum(A) / length(A)

function mean(r::AbstractRange{<:Real})
isempty(r) && throw(ArgumentError("mean of an empty range is undefined"))
function Statistics.mean(r::AbstractRange{<:Real})
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Why add a module prefix?

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Typo. Will fix.

isempty(r) && return oftype((first(r) + last(r)) / 2, NaN)
(first(r) + last(r)) / 2
end

Expand All @@ -150,7 +150,7 @@ function _var(iterable, corrected::Bool, mean)
y = iterate(iterable)
if y === nothing
T = eltype(iterable)
return typeof((abs2(zero(T)) + abs2(zero(T)))/2)(NaN)
return oftype((abs2(zero(T)) + abs2(zero(T)))/2, NaN)
end
count = 1
value, state = y
Expand Down Expand Up @@ -267,7 +267,7 @@ varm(A::AbstractArray, m; corrected::Bool=true) = _varm(A, m, corrected, :)

function _varm(A::AbstractArray{T}, m, corrected::Bool, ::Colon) where T
n = length(A)
n == 0 && return typeof((abs2(zero(T)) + abs2(zero(T)))/2)(NaN)
n == 0 && return oftype((abs2(zero(T)) + abs2(zero(T)))/2, NaN)
return centralize_sumabs2(A, m) / (n - Int(corrected))
end

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2 changes: 2 additions & 0 deletions stdlib/Statistics/test/runtests.jl
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Expand Up @@ -119,6 +119,8 @@ end
@test f(2:0.1:n) ≈ f([2:0.1:n;])
end
end
@test mean(2:1) === NaN
@test mean(big(2):1) isa BigFloat
end

@testset "var & std" begin
Expand Down