fix (sparse) : add sort_data to coo2csr procedure (#1146)

* add sort_data optional to coo2csr

* make COO inout to allow sorting

* enrich doc for sort_data in coo2csr

Author: jalvesz

doc/specs/stdlib_sparse.md

@@ -296,14 +296,16 @@ If the `diagonal` array has not been previously allocated, the `diag` subroutine
 
 ### Syntax
 
-`call ` [[stdlib_sparse_conversion(module):coo2csr(interface)]] `(coo,csr)`
+`call ` [[stdlib_sparse_conversion(module):coo2csr(interface)]] `(coo,csr[,sort_data])`
 
 ### Arguments
 
 `coo` : Shall be a `COO` type of `real` or `complex` type. It is an `intent(in)` argument.
 
 `csr` : Shall be a `CSR` type of `real` or `complex` type. It is an `intent(out)` argument.
 
+`sort_data`, `optional` : Shall be a `logical` argument to determine whether data in the COO graph should be sorted before obtaining the CSR representation. The transformation from COO to CSR depends on the former being sorted in row-major order and not having duplicate pairs. Using this boolean will call a sorting routine at the cost of extra runtime, default `.false.`. It is an `intent(in)` argument.
+
 ### Syntax
 
 `call ` [[stdlib_sparse_conversion(module):coo2csc(interface)]] `(coo,csc)`

src/sparse/stdlib_sparse_conversion.fypp

@@ -6,6 +6,7 @@
 !!
 ! This code was modified from https://github.com/jalvesz/FSPARSE by its author: Alves Jose
 module stdlib_sparse_conversion
+    use stdlib_optval, only: optval
     use stdlib_sorting, only: sort
     use stdlib_sparse_constants
     use stdlib_sparse_kinds
@@ -215,11 +216,20 @@ contains
     #:endfor
 
     #:for k1, t1, s1 in (KINDS_TYPES)
-    subroutine coo2csr_${s1}$(COO,CSR)
-        type(COO_${s1}$_type), intent(in)  :: COO
-        type(CSR_${s1}$_type), intent(out) :: CSR
+    subroutine coo2csr_${s1}$(COO, CSR, sort_data)
+        type(COO_${s1}$_type), intent(inout) :: COO
+        type(CSR_${s1}$_type), intent(out)   :: CSR
+        logical, intent(in), optional :: sort_data
+        logical :: sort_data_
         integer(ilp) :: i
 
+        sort_data_ = optval(x=sort_data, default=.false.)
+
+        if(sort_data_) then
+            call sort_coo_unique_${s1}$( COO%index, COO%data, COO%nnz, COO%nrows, COO%ncols )
+            COO%is_sorted = .true.
+        end if
+
         CSR%nnz = COO%nnz; CSR%nrows = COO%nrows; CSR%ncols = COO%ncols
         CSR%storage = COO%storage