Add matrix alloc to ext

ext/FerriteSparseMatrixCSR.jl

@@ -70,16 +70,40 @@ function Ferrite.zero_out_columns!(K::SparseMatrixCSR, ch::ConstraintHandler)
     end
 end
 
-
 function Ferrite.allocate_matrix(::Type{SparseMatrixCSR}, sp::AbstractSparsityPattern)
-    return allocate_matrix(SparseMatrixCSR{1,Float64,Int}, sp)
+    _allocate_matrix(SparseMatrixCSR{1, Float64, Int64}, sp, false)
+end
+
+function Ferrite.allocate_matrix(::Type{SparseMatrixCSR{1, Tv, Ti}}, sp::AbstractSparsityPattern) where {Tv, Ti}
+    _allocate_matrix(SparseMatrixCSR{1, Tv, Ti}, sp, false)
 end
 
-function Ferrite.allocate_matrix(::Type{MatrixType}, sp::AbstractSparsityPattern) where {Bi, Tv, Ti, MatrixType <: SparseMatrixCSR{Bi, Tv, Ti}}
-    # Allocate CSC first ...
-    K = allocate_matrix(SparseMatrixCSC{Tv, Ti}, sp)
-    # ... and transform to SparseMatrixCSR
-    return SparseMatrixCSR{Bi}(transpose(sparse(transpose(K))))
+function _allocate_matrix(::Type{SparseMatrixCSR{1, Tv, Ti}}, sp::AbstractSparsityPattern, sym::Bool) where {Tv, Ti}
+    # 1. Setup rowptr
+    rowptr = zeros(Ti, Ferrite.getnrows(sp) + 1)
+    rowptr[1] = 1
+    for (row, colidxs) in enumerate(Ferrite.eachrow(sp))
+        for col in colidxs
+            sym && row > col && continue
+            rowptr[row+1] += 1
+        end
+    end
+    cumsum!(rowptr, rowptr)
+    nnz = rowptr[end] - 1
+    # 2. Allocate colval and nzval now that nnz is known
+    colval = Vector{Ti}(undef, nnz)
+    nzval = zeros(Tv, nnz)
+    # 3. Populate colval.
+    k = 1
+    for (row, colidxs) in zip(1:Ferrite.getnrows(sp), Ferrite.eachrow(sp)) # pairs(eachrow(sp))
+        for col in colidxs
+            sym && row > col && continue
+            colval[k] = col
+            k += 1
+        end
+    end
+    S = SparseMatrixCSR{1}(Ferrite.getnrows(sp), Ferrite.getncols(sp), rowptr, colval, nzval)
+    return S
 end
 
 end