put back specialized colwise and pairwise for CorrDist (#145)

Author: KristofferC

src/metrics.jl

@@ -711,3 +711,20 @@ function _pairwise!(r::AbstractMatrix, dist::CosineDist, a::AbstractMatrix)
     end
     r
 end
+
+# CorrDist
+_centralize_colwise(x::AbstractVector) = x .- mean(x)
+_centralize_colwise(x::AbstractMatrix) = x .- mean(x, dims=1)
+function colwise!(r::AbstractVector, dist::CorrDist, a::AbstractMatrix, b::AbstractMatrix)
+    colwise!(r, CosineDist(), _centralize_colwise(a), _centralize_colwise(b))
+end
+function colwise!(r::AbstractVector, dist::CorrDist, a::AbstractVector, b::AbstractMatrix)
+    colwise!(r, CosineDist(), _centralize_colwise(a), _centralize_colwise(b))
+end
+function _pairwise!(r::AbstractMatrix, dist::CorrDist,
+                    a::AbstractMatrix, b::AbstractMatrix)
+    _pairwise!(r, CosineDist(), _centralize_colwise(a), _centralize_colwise(b))
+end
+function _pairwise!(r::AbstractMatrix, dist::CorrDist, a::AbstractMatrix)
+    _pairwise!(r, CosineDist(), _centralize_colwise(a))
+end