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restore v0.4 behavior on v0.5, fixes #880 #884

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Aug 25, 2016
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restore v0.4 behavior on v0.5, fixes #880 #884

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4 changes: 2 additions & 2 deletions src/statistics.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -327,7 +327,7 @@ function apply_statistic(stat::HistogramStatistic,
x_min = Gadfly.concrete_minimum(values)
span = x_max - x_min
binwidth = span / d
bincounts ./= sum(bincounts) * binwidth
bincounts = bincounts ./ sum(bincounts) * binwidth
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@shashi shashi Aug 24, 2016 •
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I thought this was safe. See #864

There's one more occurrence of this same line in this file. Does that work OK?

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It's not. This line causes an InexactError in the case that binwidth is a float. bincounts is always an integer array and with the new meaning of ./= on v0.5 we are trying to do an in-place update of integer array using floats causing a type coercion error, i.e. the InexactError.

julia v0.4:

julia> a = [1,2,3]
3-element Array{Int64,1}:
 1
 2
 3

julia> a ./= 2.0
3-element Array{Float64,1}:
 0.5
 1.0
 1.5

julia v0.5-rc3

julia> a = [1,2,3]
3-element Array{Int64,1}:
 1
 2
 3

julia> a ./= 2.0
ERROR: InexactError()
 in copy!(::Base.LinearFast, ::Array{Int64,1}, ::Base.LinearFast, ::Array{Float64,1}) at ./abstractarray.jl:559
 in broadcast!(::Base.#identity, ::Array{Int64,1}, ::Array{Float64,1}) at ./broadcast.jl:24

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good detective work!

@stevengj pinging you to let you know about this.

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I think that is the intended behavior.

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Yes, that is the intended behavior.

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(In-place, fused vectorized operations will be a key feature in Julia 0.6. The fact that it catches a type instability is a bonus. 😉)

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Note that your new 0.4-style code is still type-unstable. If I were you, I'd use a different variable name (binmean?) for the normalized bincounts.

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Note that your new 0.4-style code is still type-unstable.

All of Gadfly is type-unstable 😂 haha.

If I were you, I'd use a different variable name (binmean?) for the normalized bincounts.

Why is having a new variable better? binmean will still sometimes be an Int sometimes a Float64.

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@stevengj stevengj Aug 25, 2016 •
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No, I mean do binmean = bincounts ./ sum(bincounts) .* binwidth. Then bincounts is always an array of integers, and binmean is always an array of floats. In subsequent lines, work with binmean.

(I realize that it is probably not performance critical to be type-stable here, but it is better style in Julia to retain type stability if it is not too hard.)

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Ah, I see what you mean.

end

binwidth = (x_max - x_min) / d
Expand Down Expand Up @@ -384,7 +384,7 @@ function apply_statistic(stat::HistogramStatistic,

if stat.density
binwidth = x_span / d
bincounts ./= sum(bincounts) * binwidth
bincounts = bincounts ./ sum(bincounts) * binwidth
end

stack_height += bincounts[1:d]
Expand Down
5 changes: 5 additions & 0 deletions test/histogram_density.jl
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
using Gadfly, RDatasets

# see issue #880
plot(dataset("ggplot2", "diamonds"), x="Price", color="Cut",
Geom.histogram(bincount=30, density=true))