Implement zero for SparseVector (#290)

* Implement zero for SparseVector

* Update src/implementations/SparseArrays.jl

* Update test/SparseArrays.jl

Co-authored-by: Oscar Dowson <[email protected]>

---------

Co-authored-by: Oscar Dowson <[email protected]>

Author: blegat

src/implementations/SparseArrays.jl

@@ -17,6 +17,12 @@ function undef_array(
     return SparseArrays.spzeros(Tv, Ti, length(rows), length(cols))
 end
 
+function operate!(::typeof(zero), v::SparseArrays.SparseVector)
+    empty!(v.nzind)
+    empty!(v.nzval)
+    return v
+end
+
 function operate!(::typeof(zero), A::_SparseMat)
     for i in eachindex(A.colptr)
         A.colptr[i] = one(A.colptr[i])

test/SparseArrays.jl

@@ -127,6 +127,18 @@ function test_sparse_broadcast()
     return
 end
 
+function test_zero()
+    v = SparseArrays.sparsevec([1, 2], [3.0, 4.0])
+    MA.operate!(zero, v)
+    @test isempty(SparseArrays.nonzeroinds(v))
+    @test isempty(SparseArrays.nonzeros(v))
+    A = SparseArrays.sprand(Float64, 2, 2, 0.5)
+    MA.operate!(zero, A)
+    @test iszero(SparseArrays.nnz(A))
+    @test isempty(SparseArrays.nonzeros(A))
+    return
+end
+
 end  # module
 
 TestInterfaceSparseArrays.runtests()