[c++, python] fastercsx: improved duplicate coordinate handling

apis/python/src/tiledbsoma/_fastercsx.py

@@ -29,7 +29,16 @@ class CompressedMatrix:
     Export constructed matrix to SciPy (or comparable package) for use of the result.
     """
 
-    __slots__ = ("indptr", "indices", "data", "shape", "format", "sorted", "context")
+    __slots__ = (
+        "indptr",
+        "indices",
+        "data",
+        "shape",
+        "format",
+        "is_sorted",
+        "no_duplicates",
+        "context",
+    )
 
     def __init__(
         self,
@@ -38,7 +47,8 @@ def __init__(
         data: NDArrayNumber,
         shape: Tuple[int, int],
         format: Literal["csc", "csr"],
-        sorted: bool,
+        is_sorted: bool,
+        no_duplicates: bool | None,
         context: SOMATileDBContext,
     ) -> None:
         """Construct from PJV format. Not intended for direct use - use instead the
@@ -54,7 +64,8 @@ def __init__(
         self.indices = indices
         self.data = data
         self.format = format
-        self.sorted = sorted
+        self.is_sorted = is_sorted
+        self.no_duplicates = no_duplicates
         self.context = context
 
     @staticmethod
@@ -86,25 +97,15 @@ def from_ijd(
         compress_coo(
             context.native_context, (n_major, n_minor), i, j, d, indptr, indices, data
         )
+        no_duplicates = None  # aka,unknown
         if make_sorted:
-            sort_csx_indices(context.native_context, indptr, indices, data)
+            no_duplicates = sort_csx_indices(
+                context.native_context, indptr, indices, data
+            )
         return CompressedMatrix(
-            indptr, indices, data, shape, format, make_sorted, context
+            indptr, indices, data, shape, format, make_sorted, no_duplicates, context
         )
 
-    @staticmethod
-    def from_pjd(
-        p: NDArrayIndex,
-        j: NDArrayIndex,
-        d: NDArrayNumber,
-        shape: Tuple[int, int],
-        format: Literal["csc", "csr"],
-        make_sorted: bool,
-        context: SOMATileDBContext,
-    ) -> CompressedMatrix:
-        """Factory method accepting pointers, indices and data vectors."""
-        return CompressedMatrix(p, j, d, shape, format, make_sorted, context)
-
     @staticmethod
     def from_soma(
         tables: pa.Table | Sequence[pa.Table],
@@ -156,12 +157,12 @@ def dtype(self) -> npt.DTypeLike:
     def to_scipy(
         self, index: slice | None = None
     ) -> scipy.sparse.csr_matrix | scipy.sparse.csc_matrix:
-        """Extract a slice on the compressed dimension and return as a dense
+        """Extract a slice on the compressed dimension and return as a
         :class:`scipy.sparse.csr_matrix` or
         :class:`scipy.sparse.csc_matrix`.
 
         Optionally allows slicing on compressed dimension during conversion, in which case
-        an extra memory copy is avoided.
+        an extra memory copy is avoided for the SOMA fast path (no-dups).
         """
         index = index or slice(None)
         assert isinstance(index, slice)
@@ -194,7 +195,13 @@ def to_scipy(
             else (self.shape[0], n_major)
         )
         return CompressedMatrix._to_scipy(
-            indptr, indices, data, shape, self.format, self.sorted
+            indptr,
+            indices,
+            data,
+            shape,
+            self.format,
+            self.is_sorted,
+            self.no_duplicates,
         )
 
     def to_numpy(self, index: slice | None = None) -> NDArrayNumber:
@@ -246,7 +253,8 @@ def _to_scipy(
         data: NDArrayNumber,
         shape: Tuple[int, int],
         format: Literal["csc", "csr"],
-        sorted: bool,
+        is_sorted: bool,
+        no_duplicates: bool | None,
     ) -> scipy.sparse.csr_matrix | scipy.sparse.csc_matrix:
         """
         This is to bypass the O(N) scan that :meth:`sparse._cs_matrix.__init__`
@@ -258,7 +266,8 @@ def _to_scipy(
             sparse.csr_matrix((data, indices, indptr), shape=shape)
         (or the equivalent for csc_matrix)
         """
-        if sorted:
+        if is_sorted and bool(no_duplicates):
+            # Fast path for SOMA common case.
             matrix = (
                 scipy.sparse.csr_matrix.__new__(scipy.sparse.csr_matrix)
                 if format == "csr"

apis/python/src/tiledbsoma/fastercsx.cc

@@ -391,9 +391,12 @@ void compress_coo(
 
 /**
  * @brief Python binding for sort_csx_indices, which sorts minor dimension of a
- * compressed matrix
+ * compressed matrix.
+ *
+ * Returns false if the matrix contains duplicate coordinates, true if all
+ * coordinates are unique.
  */
-void sort_csx_indices(
+bool sort_csx_indices(
     std::shared_ptr<tiledbsoma::SOMAContext> ctx,
     py::array Bp,
     py::array Bj,
@@ -414,10 +417,10 @@ void sort_csx_indices(
         value_type_dispatch, Bd.dtype(), "CSx data array");
 
     // Dispatch by type
-    std::visit(
+    auto no_duplicates = std::visit(
         [&](auto value_type,
             auto csx_major_index_type,
-            auto csx_minor_index_type) {
+            auto csx_minor_index_type) -> bool {
             using CSX_MAJOR_INDEX =
                 typename decltype(csx_major_index_type)::type;
             using CSX_MINOR_INDEX =
@@ -446,6 +449,8 @@ void sort_csx_indices(
         value_type,
         csx_major_index_type,
         csx_minor_index_type);
+
+    return no_duplicates;
 };
 
 /**

apis/python/tests/test_fastercsx.py

@@ -56,7 +56,7 @@ def assert_eq(sp: sparse.spmatrix, cm: fastercsx.CompressedMatrix) -> bool:
     assert cm.indptr.shape == sp_csx.indptr.shape
 
     assert np.array_equal(cm.indptr, sp_csx.indptr)
-    if cm.sorted:
+    if cm.is_sorted:
         assert np.array_equal(cm.indices, sp_csx.indices)
         assert np.array_equal(cm.data, sp_csx.data)
 
@@ -93,22 +93,6 @@ def test_from_ijd(
     assert cm.to_scipy().has_canonical_format
 
 
-def test_from_pjd(context: soma.SOMATileDBContext, rng: np.random.Generator) -> None:
-    sp = sparse.random(
-        9970, 3124, density=0.01, dtype=np.float32, random_state=rng
-    ).tocsr()
-    cm = fastercsx.CompressedMatrix.from_pjd(
-        sp.indptr,
-        sp.indices,
-        sp.data,
-        sp.shape,
-        format="csr",
-        make_sorted=True,
-        context=context,
-    )
-    assert_eq(sp, cm)
-
-
 @pytest.mark.parametrize("format", ["csr", "csc"])
 @pytest.mark.parametrize("n_tables", [1, 2, 3])
 @pytest.mark.parametrize(
@@ -361,3 +345,24 @@ def test_bad_shapes(context: soma.SOMATileDBContext, rng: np.random.Generator) -
             fastercsx.CompressedMatrix.from_ijd(
                 sp.row, sp.col, sp.data, shp, "csr", True, context
             )
+
+
+@pytest.mark.parametrize("format", ["csr", "csc"])
+@pytest.mark.parametrize("make_sorted", [True, False])
+def test_duplicates(
+    format: str,
+    make_sorted: bool,
+    context: soma.SOMATileDBContext,
+    rng: np.random.Generator,
+) -> None:
+    shape = (10, 10)
+    i = np.array([0, 0, 1, 1], dtype=np.int64)
+    j = np.array([0, 0, 1, 1], dtype=np.int64)
+    d = np.arange(len(i), dtype=np.int8)
+
+    cm = fastercsx.CompressedMatrix.from_ijd(
+        i, j, d, shape, format, make_sorted, context
+    )
+    assert (
+        sparse.coo_matrix((d, (i, j)), shape=shape).asformat(format) != cm.to_scipy()
+    ).nnz == 0

apis/python/tests/test_libfastercsx.py

@@ -85,7 +85,7 @@ def test_construction(
         indices,
         data,
     )
-    fastercsx.sort_csx_indices(context, indptr, indices, data)
+    assert fastercsx.sort_csx_indices(context, indptr, indices, data)
 
     # Verify equality with SciPy constructed CSR
     csr = sp.tocsr()
@@ -144,7 +144,7 @@ def test_partitioning(
         indices,
         data,
     )
-    fastercsx.sort_csx_indices(context, indptr, indices, data)
+    assert fastercsx.sort_csx_indices(context, indptr, indices, data)
 
     # Verify equality with SciPy constructed CSR
     csr = sp.tocsr()
@@ -194,7 +194,7 @@ def test_multichunk(
         indices,
         data,
     )
-    fastercsx.sort_csx_indices(context, indptr, indices, data)
+    assert fastercsx.sort_csx_indices(context, indptr, indices, data)
 
     # Verify equality with SciPy constructed CSR
     csr = sp.tocsr()
@@ -334,3 +334,31 @@ def test_ragged_chunk_error(
             indices,
             data,
         )
+
+
+def test_empty_first_frag(rng: np.random.Generator, context: clib.SOMAContext) -> None:
+    fastercsx.compress_coo(
+        context,
+        shape := (56, 18),
+        (
+            np.array([], dtype=np.int32),
+            i := np.array([9, 35, 20, 7, 46, 41, 16, 28, 8, 19], dtype=np.int32),
+        ),
+        (
+            np.array([], dtype=np.int32),
+            j := np.array([15, 14, 11, 9, 4, 0, 0, 5, 3, 1], dtype=np.int32),
+        ),
+        (
+            np.array([], dtype=np.int8),
+            d := np.array([85, 63, 51, 26, 30, 4, 7, 1, 17, 81], dtype=np.int8),
+        ),
+        indptr := np.zeros(57, dtype=np.int32),
+        indices := np.empty((10,), dtype=np.int32),
+        data := np.empty((10,), dtype=np.int8),
+    )
+
+    csr = sparse.csr_matrix((d, (i, j)), shape=shape)
+    assert (csr != sparse.csr_matrix((data, indices, indptr), shape=shape)).nnz == 0
+    assert np.array_equal(csr.indptr, indptr)
+    assert np.array_equal(csr.indices, indices)
+    assert np.array_equal(csr.data, data)

libtiledbsoma/src/utils/fastercsx.h

@@ -215,16 +215,15 @@ void count_rows_(
     } else if (n_partitions > 0) {
         // for a single partition, just accumulate directly into the output
         // array
-        assert(Ai.size() == 1);
-        assert(
-            Ai[0].data() == partitions[0].views[0].data() &&
-            Ai[0].size() == partitions[0].views[0].size());
-        auto& Ai_view = Ai[0];
-        for (uint64_t n = 0; n < nnz; ++n) {
-            uint64_t row = Ai_view[n];
-            if ((row > n_row - 1) || (row < 0)) [[unlikely]]
-                throw std::out_of_range("Coordinate out of range.");
-            Bp[row]++;
+        for (auto& Ai_view : partitions[0].views) {
+            for (size_t n = 0; n < Ai_view.size(); n++) {
+                auto row = Ai_view[n];
+                if ((row < 0) ||
+                    (static_cast<std::make_unsigned_t<COO_IDX>>(row) >= n_row))
+                    [[unlikely]]
+                    throw std::out_of_range("Coordinate out of range.");
+                Bp[row]++;
+            }
         }
     }
     // else, zero length array
@@ -435,9 +434,12 @@ bool index_lt_(
 
 /**
  * @brief In-place sort of minor axis, used to canonicalize the CSx ordering.
+ *
+ * Returns false if there are duplicate coordinates, true if all coordinates
+ * are unique.
  */
 template <class VALUE, class CSX_MINOR_IDX, class CSX_MAJOR_IDX>
-void sort_csx_indices(
+bool sort_csx_indices(
     ThreadPool* const tp,
     uint64_t n_row,
     uint64_t nnz,
@@ -448,8 +450,10 @@ void sort_csx_indices(
     assert(Bj.size() == nnz);
     assert(Bd.size() == nnz);
 
+    bool no_duplicates = true;
+
     auto status = parallel_for(
-        tp, 0ul, n_row, [&Bp, &Bj, &Bd, &nnz](uint64_t row) {
+        tp, 0ul, n_row, [&Bp, &Bj, &Bd, &nnz, &no_duplicates](uint64_t row) {
             uint64_t idx_start = Bp[row];
             uint64_t idx_end = Bp[row + 1];
 
@@ -468,12 +472,16 @@ void sort_csx_indices(
             for (uint64_t n = 0, idx = idx_start; idx < idx_end; ++n, ++idx) {
                 Bj[idx] = temp[n].first;
                 Bd[idx] = temp[n].second;
+
+                if (n > 0 && Bj[idx] == Bj[idx - 1])
+                    no_duplicates = false;
             }
 
             return Status::Ok();
         });
 
     assert(status.ok());
+    return no_duplicates;
 };
 
 /**