ANN: TypeSortedCollections.jl


#1

I recently wrote and registered TypeSortedCollections.jl, a small package that allows you to perform operations on a type-heterogeneous collection in type-stable and statically dispatched fashion. I originally implemented this for use in RigidBodyDynamics.jl, but decided to pull it out into its own package as I hope it will be useful for others as well.

TypeSortedCollections provides the TypeSortedCollection type, which sorts a type-heterogeneous input collection by type upon construction, and stores the elements in a Tuple of concretely typed Vectors, one for each type. TypeSortedCollections provides type stable methods for map!, foreach, and mapreduce that take at least one TypeSortedCollection.

An example (from the readme):

julia> using TypeSortedCollections

julia> f(x::Int64, y::Float64) = x * y
f (generic function with 2 methods)

julia> f(x::Float64, y::Float64) = round(Int64, -x * y)
f (generic function with 2 methods)

julia> xs = Number[1.; 2; 3]; # note the abstract element type; contains both Float64 and Int64

julia> sortedxs = TypeSortedCollection(xs);

julia> ys = [1.; 2.; 3.];

julia> results = Vector{Int64}(length(xs));

julia> map!(f, results, sortedxs, ys)
3-element Array{Int64,1}:
 -1
  4
  9

julia> @allocated map!(f, results, sortedxs, ys)
0

Please check out the readme for additional features and notes (especially on when TypeSortedCollections are appropriate to use), and let me know if you have any questions!