Light interface

.gitignore

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+*DS_Store
+Manifest.toml

.travis.yml

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+# Documentation: http://docs.travis-ci.com/user/languages/julia/
+language: julia
+os:
+  - linux
+julia:
+  - 1.1
+  - 1.2
+  - 1.3
+  - 1.4
+  - nightly
+matrix:
+  allow_failures:
+    - julia: nightly
+notifications:
+  email: false
+after_success:
+  # push coverage results to Codecov
+  - julia -e 'using Pkg; pkg"add Coverage"; using Coverage; Codecov.submit(Codecov.process_folder())'

Manifest.toml

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+# This file is machine-generated - editing it directly is not advised
+
+[[ScientificTypes]]
+git-tree-sha1 = "661a775ebf854f14509f590952eba63b47c82a5f"
+uuid = "321657f4-b219-11e9-178b-2701a2544e81"
+version = "0.6.0"

Project.toml

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+name = "MLJModelInterface"
+uuid = "e80e1ace-859a-464e-9ed9-23947d8ae3ea"
+authors = ["Thibaut Lienart <ltib@me.com>"]
+version = "0.1.0"
+
+[deps]
+ScientificTypes = "321657f4-b219-11e9-178b-2701a2544e81"
+
+[compat]
+ScientificTypes = "^0.6"
+
+[extras]
+Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
+Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
+
+[targets]
+test = ["Test", "Tables"]

src/MLJModelInterface.jl

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+module MLJModelInterface
+
+# ------------------------------------------------------------------------
+# Dependency (note that ScientificTypes itself does not have dependencies)
+import ScientificTypes: trait
+
+# ------------------------------------------------------------------------
+# Single export: matrix, everything else is qualified in MLJBase
+export matrix
+
+# ------------------------------------------------------------------------
+
+abstract type Mode end
+struct LightInterface <: Mode end
+struct FullInterface  <: Mode end
+
+const INTERFACE_MODE = Ref{Mode}(LightInterface())
+
+set_interface_mode(m::Mode) = (INTERFACE_MODE[] = m)
+
+get_interface_mode() = INTERFACE_MODE[]
+
+struct InterfaceError <: Exception
+    m::String
+end
+
+vtrait(X) = X |> trait |> Val
+
+"""
+    matrix(X; transpose=false)
+
+If `X <: AbstractMatrix`, return `X` or `permutedims(X)` if `transpose=true`.
+If `X` is a Tables.jl compatible table source, convert `X` into a `Matrix`.
+"""
+matrix(X; kw...) = matrix(vtrait(X), X, get_interface_mode(); kw...)
+
+matrix(::Val{:other}, X::AbstractMatrix, ::Mode; transpose=false) =
+    transpose ? permutedims(X) : X
+
+matrix(::Val{:other}, X, ::Mode; kw...) =
+    throw(ArgumentError("Function `matrix` only supports AbstractMatrix or " *
+                        "containers implementing the Tables interface."))
+
+matrix(::Val{:table}, X, ::LightInterface; kw...) =
+    throw(InterfaceError("Only `MLJModelInterface` loaded. Import `MLJBase`."))
+
+end # module

test/runtests.jl

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+using Test, MLJModelInterface, ScientificTypes
+using Tables
+
+const M = MLJModelInterface
+
+ScientificTypes.TRAIT_FUNCTION_GIVEN_NAME[:table] = Tables.istable
+
+@testset "light-interface" begin
+    M.set_interface_mode(M.LightInterface())
+    @test M.get_interface_mode() isa M.LightInterface
+
+    # matrix object (:other)
+    X   = zeros(3, 4)
+    mX  = matrix(X)
+    mtX = matrix(X; transpose=true)
+
+    @test mX === X
+    @test mtX == permutedims(X)
+
+    # :other but not matrix
+    X = (1, 2, 3, 4)
+    @test_throws ArgumentError matrix(X)
+
+    # :table
+    X = (x=[1,2,3], y=[1,2,3])
+    @test M.vtrait(X) isa Val{:table}
+    @test_throws M.InterfaceError matrix(X)
+end
+
+@testset "full-interface" begin
+    M.set_interface_mode(M.FullInterface())
+    @test M.get_interface_mode() isa M.FullInterface
+
+    M.matrix(::Val{:table}, X, ::M.FullInterface; kw...) =
+        Tables.matrix(X; kw...)
+
+    X = (x=[1,2,3], y=[1,2,3])
+    mX = matrix(X)
+    @test mX isa Matrix
+    @test mX == hcat(X.x, X.y)
+end