Support CartesianIndex indexing when mixed with Real (#184)

Fixes #183

Author: timholy

src/Interpolations.jl

@@ -94,6 +94,18 @@ eltype(::Type{ITP}) where {ITP<:AbstractInterpolation} = eltype(supertype(ITP))
 eltype(itp::AbstractInterpolation) = eltype(typeof(itp))
 count_interp_dims(::Type{T}, N) where {T<:AbstractInterpolation} = N
 
+# Generic indexing methods (fixes #183)
+Base.to_index(::AbstractInterpolation, i::Real) = i
+
+@inline function Base._getindex(::IndexCartesian, A::AbstractInterpolation{T,N}, I::Vararg{Int,N}) where {T,N} # ambiguity resolution
+    @inbounds r = getindex(A, I...)
+    r
+end
+@inline function Base._getindex(::IndexCartesian, A::AbstractInterpolation{T,N}, I::Vararg{Real,N}) where {T,N}
+    @inbounds r = getindex(A, I...)
+    r
+end
+
 include("nointerp/nointerp.jl")
 include("b-splines/b-splines.jl")
 include("gridded/gridded.jl")

test/b-splines/linear.jl

@@ -41,4 +41,10 @@ for (constructor, copier) in ((interpolate, identity), (interpolate!, copy))
     end
 end
 
+# Issue #183
+x = rand(3,3,3)
+itp = interpolate(x, BSpline(Linear()), OnGrid())
+@test itp[1.5, CartesianIndex((2, 3))] === itp[1.5, 2, 3]
+@test itp[CartesianIndex((1, 2)), 1.5] == itp[1, 2, 1.5]
+
 end