Determine size automatically in sparse

Author: mtfishman

src/abstractsparsearray.jl

@@ -41,7 +41,8 @@ end
 
 Construct an `N`-dimensional [`SparseArrayDOK`](@ref) containing elements of type `T`. Both
 `T` and `N` can either be supplied explicitly or be determined by the `storage` and the
-length or number of `dims`.
+length or number of `dims`. If `dims` aren't specified, the size will be determined automatically
+from the input indices.
 
 This constructor does not take ownership of the supplied storage, and will result in an
 independent container.
@@ -60,6 +61,14 @@ end
 function sparse(storage::AbstractDictOrDictionary, dims::Int...; kwargs...)
   return sparse(storage, dims; kwargs...)
 end
+# Determine the size automatically.
+function sparse(storage::AbstractDictOrDictionary; kwargs...)
+  dims = ntuple(Returns(0), length(keytype(storage)))
+  for I in keys(storage)
+    dims = map(max, dims, Tuple(I))
+  end
+  return sparse(storage, dims; kwargs...)
+end
 
 using Random: Random, AbstractRNG, default_rng
 

test/test_sparsearraydok.jl

@@ -1,5 +1,6 @@
 using Adapt: adapt
 using ArrayLayouts: zero!
+using Dictionaries: Dictionary
 using JLArrays: JLArray, @allowscalar
 using SparseArraysBase:
   SparseArraysBase,
@@ -222,22 +223,29 @@ arrayts = (Array,)
   @test a == [11 12; 12 22]
   @test storedlength(a) == 4
 
-  d = Dict([CartesianIndex(1, 2) => elt(12), CartesianIndex(2, 1) => elt(21)])
-  for a in (
-    sparse(d, 2, 2),
-    sparse(d, 2, 2; getunstored=Returns(zero(elt))),
-    sparse(d, (2, 2)),
-    sparse(d, (2, 2); getunstored=Returns(zero(elt))),
+  for d in (
+    Dict([CartesianIndex(1, 2) => elt(12), CartesianIndex(2, 1) => elt(21)]),
+    Dictionary([CartesianIndex(1, 2), CartesianIndex(2, 1)], [elt(12), elt(21)]),
   )
-    @test !iszero(a)
-    @test iszero(a[1, 1])
-    @test a[2, 1] == elt(21)
-    @test a[1, 2] == elt(12)
-    @test iszero(a[2, 2])
-    @test size(a) == (2, 2)
-    @test storedlength(a) == 2
-    @test eltype(a) === elt
-    @test a isa SparseMatrixDOK{elt}
+    for a in (
+      sparse(d, 2, 2),
+      sparse(d, 2, 2; getunstored=Returns(zero(elt))),
+      sparse(d, (2, 2)),
+      sparse(d, (2, 2); getunstored=Returns(zero(elt))),
+      # Determine the size automatically.
+      sparse(d),
+      sparse(d; getunstored=Returns(zero(elt))),
+    )
+      @test !iszero(a)
+      @test iszero(a[1, 1])
+      @test a[2, 1] == elt(21)
+      @test a[1, 2] == elt(12)
+      @test iszero(a[2, 2])
+      @test size(a) == (2, 2)
+      @test storedlength(a) == 2
+      @test eltype(a) === elt
+      @test a isa SparseMatrixDOK{elt}
+    end
   end
 
   for (a, elt′) in (