Added findaxis, finddim, and hasdim

src/ImageCore.jl

@@ -76,6 +76,9 @@ export
     # traits
     assert_timedim_last,
     coords_spatial,
+    findaxis,
+    finddim,
+    hasdim,
     height,
     indices_spatial,
     namedaxes,

src/traits.jl

@@ -31,26 +31,83 @@ is the corresponding dimensions's axis. If `HasDimNames` is not defined for `x`
 default names are returned. `x` should have an `axes` method.
 
 ```jldoctest
-julia> using ImagesCore
+julia> using ImageCore
 
 julia> img = reshape(1:24, 2,3,4);
 
 julia> namedaxes(img)
-(dim_1 = Base.OneTo(2), dim_2 = Base.OneTo(3), dim_3 = Base.OneTo(4))
+(:row = Base.OneTo(2), :col = Base.OneTo(3), :page = Base.OneTo(4))
 ```
 """
-namedaxes(img::T) where T = namedaxes(HasDimNames(T), img)
+namedaxes(img::T) where T = _namedaxes(HasDimNames(T), img)
+_namedaxes(::HasDimNames{true}, img) = NamedTuple{names(img)}(axes(img))
+_namedaxes(::HasDimNames{false}, img) = NamedTuple{default_names(img)}(axes(img))
+
+default_names(img::AbstractArray{T,N}) where {T,N} = ntuple(i->default_name(i), N)
+
+@inline function default_name(i::Integer)
+    if i == 1
+        return :row
+    elseif i == 2
+        return :col
+    elseif i == 3
+        return :page
+    else
+        return Symbol(:dim_, i)
+    end
+end
 
-namedaxes(::HasDimNames{true}, x::T) where T = NamedTuple{names(x)}(axes(x))
+"""
+    findaxis(img, name) -> axis
 
-function namedaxes(::HasDimNames{false}, img::AbstractArray{T,N}) where {T,N}
-    NamedTuple{default_names(Val(N))}(axes(img))
+Returns the axis (as in `axes(img, dim)`) that corresponds to the `name`. If no
+matching name is found any empy axis (i.e. `0:0`) is returned.
+"""
+@inline findaxis(A, name::Symbol) = _findaxis(namedaxes(A), name)
+function _findaxis(nt::NamedTuple{syms}, name::Symbol) where {syms}
+    if __hasdim(syms, name)
+        return getfield(nt, name)
+    else
+        return 0:-1
+    end
 end
 
-@generated function default_names(img::Val{N}) where {N}
-    :($(ntuple(i -> Symbol(:dim_, i), N)))
+"""
+    finddim(img, name) -> Int
+
+Returns the dimension that has the corresponding `name`. If `name` doesn't
+match any of the dimension names `0` is returned. If `img` doesn't have `names`
+then the default set of names is searched (e.g., dim_1, dim_2, ...).
+"""
+@inline finddim(A::T, name::Symbol) where {T} = _finddim(HasDimNames(T), A, name)
+_finddim(::HasDimNames{false}, A::T, name::Symbol) where {T} = __finddim(default_names(A), name)
+_finddim(::HasDimNames{true}, A::T, name::Symbol) where {T} = __finddim(names(A), name)
+
+Base.@pure function __finddim(dimnames::NTuple{N,Symbol}, name::Symbol) where {N}
+    for i in 1:N
+        getfield(dimnames, i) === name && return i
+    end
+    return 0
 end
 
+
+"""
+    hasdim(x, name) -> Bool
+
+Returns `true` if `name` is present.
+"""
+hasdim(x::T, name::Symbol) where {T} = _hasdim(HasDimNames(T), x, name)
+_hasdim(::HasDimNames{true}, x::T, name::Symbol) where {T} = __hasdim(names(x), name)
+_hasdim(::HasDimNames{false}, x::T, name::Symbol) where {T} = __hasdim(default_names(x), name)
+
+Base.@pure function __hasdim(dimnames::Tuple{Vararg{Symbol,N}}, name::Symbol) where {N}
+    for ii in 1:N
+        getfield(dimnames, ii) === name && return true
+    end
+    return false
+end
+
+
 """
     pixelspacing(img) -> (sx, sy, ...)
 

test/traits.jl

@@ -169,21 +169,38 @@ ImageCore.HasProperties(::Type{<:RowVector}) = HasProperties{true}()
 
 Base.names(::RowVector) = (:row,)
 Base.axes(rv::RowVector) = axes(rv.v)
-
+Base.size(rv::RowVector) = size(rv.v)
 
 @testset "Trait Interface" begin
     img = reshape(1:24, 2,3,4)
-    @test @inferred(namedaxes(img)) == NamedTuple{(:dim_1, :dim_2, :dim_3)}(axes(img))
+    @test @inferred(namedaxes(img)) == NamedTuple{(:row, :col, :page)}(axes(img))
     @test @inferred(HasDimNames(img)) == HasDimNames{false}()
     @test @inferred(HasProperties(img)) == HasProperties{false}()
 
-    rv = RowVector([1:10...], Dict{String,Any}())
+    rv = RowVector([1:10...], Dict{String,Any}());
     @test @inferred(HasDimNames(rv)) == HasDimNames{true}()
     @test @inferred(HasProperties(rv)) == HasProperties{true}()
     @test @inferred(namedaxes(rv)) == NamedTuple{(:row,)}((Base.OneTo(10),))
 
+    @test @inferred(hasdim(rv, :row)) == true
+    @test @inferred(hasdim(rv, :time)) == false
+    @test @inferred(hasdim(img, :time)) == false
+
+    @test @inferred(finddim(rv, :time)) == 0
+    @test @inferred(finddim(rv, :row)) == 1
+    @test @inferred(finddim(img, :page)) == 3
+
+    @test findaxis(rv, :time) == 0:-1
+    @test findaxis(rv, :row) == Base.OneTo(10)
+    @test findaxis(img, :page) == Base.OneTo(4)
+
     # default names
-    @test @inferred(default_names(Val(3))) == (:dim_1, :dim_2, :dim_3)
+    @test @inferred(default_names(img)) == (:row, :col, :page)
+    @test @inferred(ImageCore.default_name(1)) == :row
+    @test @inferred(ImageCore.default_name(2)) == :col
+    @test @inferred(ImageCore.default_name(3)) == :page
+    @test @inferred(ImageCore.default_name(4)) == :dim_4
+
 end
 
 nothing