Add Compat.repeat() accepting any AbstractArray

Compatibility for JuliaLang/julia#14082. Since the new version in
Julia 0.5 calls similar() internally, it is not enough to wrap it
into a compatibility function to backport the fix. This is required
to deprecate rep() from DataArrays.jl, which provides similar
functionality for two custom array types.

Author: nalimilan

README.md

@@ -213,6 +213,8 @@ Currently, the `@compat` macro supports the following syntaxes:
   Compat provides an unexported `Compat.AsyncCondition` type that is aliased to
   `Base.SingleAsyncWork` on Julia 0.3 and 0.4 and `Base.AsyncCondition` on Julia 0.5.
 
+* `repeat` now accepts any `AbstractArray` [#14082](https://github.com/JuliaLang/julia/pull/14082): `Compat.repeat` supports this new API on Julia 0.4, and calls `Base.repeat` on 0.5.
+
 ## New types
 
 * [`Nullable` types](http://julia.readthedocs.org/en/latest/manual/types/?highlight=nullable#nullable-types-representing-missing-values) and their associated operations.

src/Compat.jl

@@ -1138,4 +1138,49 @@ if !isdefined(Base, @compat Symbol("@static"))
     export @static
 end
 
+# JuliaLang/julia#14082
+if VERSION < v"0.5.0-dev+4295" && VERSION >= v"0.4"
+    function repeat(A::AbstractArray;
+                    inner=ntuple(x->1, ndims(A)),
+                    outer=ntuple(x->1, ndims(A)))
+        ndims_in = ndims(A)
+        length_inner = length(inner)
+        length_outer = length(outer)
+
+        length_inner >= ndims_in || throw(ArgumentError("number of inner repetitions ($(length(inner))) cannot be less than number of dimensions of input ($(ndims(A)))"))
+        length_outer >= ndims_in || throw(ArgumentError("number of outer repetitions ($(length(outer))) cannot be less than number of dimensions of input ($(ndims(A)))"))
+
+        ndims_out = max(ndims_in, length_inner, length_outer)
+
+        inner = vcat(collect(inner), ones(Int,ndims_out-length_inner))
+        outer = vcat(collect(outer), ones(Int,ndims_out-length_outer))
+
+        size_in = size(A)
+        size_out = ntuple(i->inner[i]*size(A,i)*outer[i],ndims_out)::Dims
+        inner_size_out = ntuple(i->inner[i]*size(A,i),ndims_out)::Dims
+
+        indices_in = Vector{Int}(ndims_in)
+        indices_out = Vector{Int}(ndims_out)
+
+        length_out = prod(size_out)
+        R = similar(A, size_out)
+
+        for index_out in 1:length_out
+            ind2sub!(indices_out, size_out, index_out)
+            for t in 1:ndims_in
+                # "Project" outer repetitions into inner repetitions
+                indices_in[t] = mod1(indices_out[t], inner_size_out[t])
+                # Find inner repetitions using flooring division
+                indices_in[t] = Base.fld1(indices_in[t], inner[t])
+            end
+            index_in = sub2ind(size_in, indices_in...)
+            R[index_out] = A[index_in]
+        end
+
+        return R
+    end
+else
+    const repeat = Base.repeat
+end
+
 end # module

test/runtests.jl

@@ -1147,3 +1147,9 @@ end
 else
     @test VERSION < v"0.4"
 end
+
+if VERSION >= v"0.4"
+    @test Compat.repeat(1:2, inner=2) == [1, 1, 2, 2]
+    @test Compat.repeat(1:2, outer=[2]) == [1, 2, 1, 2]
+    @test Compat.repeat([1,2], inner=(2,)) == [1, 1, 2, 2]
+end