Support abs2

Author: timholy

Project.toml

@@ -1,6 +1,6 @@
 name = "ColorVectorSpace"
 uuid = "c3611d14-8923-5661-9e6a-0046d554d3a4"
-version = "0.9.5"
+version = "0.9.6"
 
 [deps]
 ColorTypes = "3da002f7-5984-5a60-b8a6-cbb66c0b333f"

README.md

@@ -113,17 +113,9 @@ RGBRGB{Float64}:
 
 ### `abs` and `abs2`
 
-To begin with, there is no general and straightforward definition of the
-absolute value of a vector.
 There are roughly two possible definitions of `abs`/`abs2`: as a channel-wise
 operator or as a function which returns a real number based on the norm.
 For the latter, there are also variations in the definition of norm.
 
 In ColorVectorSpace v0.9 and later, `abs` is defined as a channel-wise operator
-and `abs2` is undefined.
-The following are alternatives for the definitions in ColorVectorSpace v0.8 and
-earlier.
-```julia
-_abs(c)  = mapreducec(v->abs(float(v)), +, 0, c)
-_abs2(c) = mapreducec(v->float(v)^2, +, 0, c)
-```
+and `abs2` returns a scalar, and `abs2(c) == c⋅c ≈ norm(c)^2`.

src/ColorVectorSpace.jl

@@ -41,6 +41,10 @@ if !hasmethod(zero, (Type{TransparentGray},))
     zero(p::Colorant) = zero(typeof(p))
 end
 
+if !hasmethod(one, (Type{Gray24},))
+    Base.one(::Type{Gray24}) = Gray24(1)
+end
+
 if !hasmethod(one, (Type{TransparentGray},)) # specification change is planned for ColorTypes v0.12
     Base.one(::Type{C}) where {C<:TransparentGray} = C(1,1)
     Base.one(::Type{C}) where {C<:AbstractRGB}     = C(1,1,1)
@@ -242,6 +246,7 @@ copy(c::MathTypes) = c
 (-)(c::MathTypes{Bool}) = c
 abs(c::MathTypes) = mapc(abs, c)
 norm(c::MathTypes, p::Real=2) = (cc = channels(c); norm(cc, p)/(p == 0 ? length(cc) : length(cc)^(1/p)))
+Base.abs2(c::MathTypes) = c ⋅ c
 (⊙)(a::C, b::C) where {C<:MathTypes} = _mapc(rettype(*, a, b), _mul, a, b)
 (⋅)(a::C, b::C) where {C<:MathTypes} = throw(MethodError(dot, (a, b)))
 (⊗)(a::C, b::C) where {C<:MathTypes} = throw(MethodError(tensor, (a, b)))

test/runtests.jl

@@ -116,7 +116,7 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         @test_throws MethodError cf ÷ cf
         @test cf + 0.1     === 0.1 + cf        === Gray(Float64(0.1f0) + 0.1)
         @test cf64 - 0.1f0 === -(0.1f0 - cf64) === Gray( 0.2 - Float64(0.1f0))
-        @test_throws MethodError abs2(ccmp)
+        @test abs2(ccmp) === abs2(gray(ccmp))
         @test norm(cf) == norm(cf, 2) == norm(gray(cf))
         @test norm(cf, 1)   == norm(gray(cf), 1)
         @test norm(cf, Inf) == norm(gray(cf), Inf)
@@ -384,7 +384,9 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         @test isinf(RGB(1, Inf, 0.5))
         @test !isnan(RGB(1, Inf, 0.5))
         @test abs(RGB(0.1,0.2,0.3)) == RGB(0.1,0.2,0.3)
-        @test_throws MethodError abs2(RGB(0.1,0.2,0.3))
+        cv = RGB(0.1,0.2,0.3)
+        @test abs2(cv) == cv ⋅ cv
+        @test abs2(cv) ≈ norm(cv)^2
         @test_throws MethodError sum(abs2, RGB(0.1,0.2,0.3))
         @test norm(RGB(0.1,0.2,0.3)) ≈ sqrt(0.14)/sqrt(3)
 
@@ -774,6 +776,8 @@ ColorTypes.comp2(c::RGBA32) = alpha(c)
         @test varmult(⊙, cs, dims=2) ≈ 2*[v1, v1, v1]
         v2 = RGB(0.1^2, 0.01^2, 0.03^2)
         @test varmult(⊙, cs, dims=1) ≈ [v2 v2]
+
+        @test var(cs) == varmult(⋅, cs)
     end
 
     @testset "copy" begin