Add copy parameter to functions returning Arrow views (#107)

python/python/geoindex_rs/rtree.pyi

@@ -23,18 +23,24 @@ IndexLike = Union[np.ndarray, ArrowArrayExportable, Buffer, RTree]
 """A type alias for accepted input as an RTree.
 """
 
-def boxes_at_level(index: IndexLike, level: int) -> Array:
+def boxes_at_level(index: IndexLike, level: int, *, copy: bool = False) -> Array:
     """Access the raw bounding box data contained in the RTree at a given tree level.
 
     Args:
         index: the RTree to search.
         level: The level of the tree to read from. Level 0 is the _base_ of the tree. Each integer higher is one level higher of the tree.
 
+    Other Args:
+        copy: if True, make a _copy_ of the data from the underlying RTree instead of
+            viewing it directly. Making a copy can be preferred if you'd like to delete
+            the index itself to save memory.
+
     Returns:
         An Arrow FixedSizeListArray containing the bounding box coordinates.
 
-            The returned array is a a zero-copy view from Rust. Note that it will keep
-            the entire index memory alive until the returned array is garbage collected.
+            If `copy` is `False`, the returned array is a a zero-copy view from Rust.
+            Note that it will keep the entire index memory alive until the returned
+            array is garbage collected.
     """
 
 def tree_join(
@@ -106,7 +112,7 @@ def neighbors(
         An Arrow array with the insertion indexes of query results.
     """
 
-def partitions(index: IndexLike) -> RecordBatch:
+def partitions(index: IndexLike, *, copy=False) -> RecordBatch:
     """Extract the spatial partitions from an RTree.
 
     This can be used to find the sorted groups for spatially partitioning the original
@@ -144,15 +150,21 @@ def partitions(index: IndexLike) -> RecordBatch:
     Args:
         index: the RTree to use.
 
+    Other Args:
+        copy: if True, make a _copy_ of the data from the underlying RTree instead of
+            viewing it directly. Making a copy can be preferred if you'd like to delete
+            the index itself to save memory.
+
     Returns:
         An Arrow `RecordBatch` with two columns: `indices` and `partition_ids`. `indices` refers to the insertion index of each row and `partition_ids` refers to the partition each row belongs to.
 
-            The `indices` column is constructed as a zero-copy view on the provided
-            index. Therefore, the `indices` array will have type `uint16` if the tree
-            has fewer than 16,384 items; otherwise it will have type `uint32`.
+            If `copy` is `False`, the `indices` column is constructed as a zero-copy
+            view on the provided index. Therefore, the `indices` array will have type
+            `uint16` if the tree has fewer than 16,384 items; otherwise it will have
+            type `uint32`.
     """
 
-def partition_boxes(index: IndexLike) -> RecordBatch:
+def partition_boxes(index: IndexLike, *, copy: bool = False) -> RecordBatch:
     """Extract the geometries of the spatial partitions from an RTree.
 
     In order for these boxes to be zero-copy from Rust, they are returned as a
@@ -169,12 +181,18 @@ def partition_boxes(index: IndexLike) -> RecordBatch:
     Args:
         index: the RTree to use.
 
+    Other Args:
+        copy: if True, make a _copy_ of the data from the underlying RTree instead of
+            viewing it directly. Making a copy can be preferred if you'd like to delete
+            the index itself to save memory.
+
     Returns:
         An Arrow `RecordBatch` with two columns: `boxes` and `partition_ids`. `boxes` stores the box geometry of each partition and `partition_ids` refers to the partition each row belongs to.
 
-            The `boxes` column is constructed as a zero-copy view on the internal boxes
-            data. The `partition_id` column will be `uint16` type if there are less than
-            65,536 partitions; otherwise it will be `uint32` type.
+            If `copy` is `False`, the `boxes` column is constructed as a zero-copy view
+            on the internal boxes data. The `partition_id` column will be `uint16` type
+            if there are less than 65,536 partitions; otherwise it will be `uint32`
+            type.
     """
 
 def search(

python/src/rtree/boxes_at_level.rs

@@ -8,19 +8,25 @@ use crate::rtree::input::PyRTreeRef;
 use crate::util::boxes_to_arrow;
 
 #[pyfunction]
-pub fn boxes_at_level(py: Python, index: PyRTreeRef, level: usize) -> PyResult<PyObject> {
+#[pyo3(signature = (index, level, *, copy = false))]
+pub fn boxes_at_level(
+    py: Python,
+    index: PyRTreeRef,
+    level: usize,
+    copy: bool,
+) -> PyResult<PyObject> {
     let array = match index {
         PyRTreeRef::Float32(tree) => {
             let boxes = tree
                 .boxes_at_level(level)
                 .map_err(|err| PyIndexError::new_err(err.to_string()))?;
-            boxes_to_arrow::<Float32Type>(boxes, tree.buffer().clone())
+            boxes_to_arrow::<Float32Type>(boxes, tree.buffer().clone(), copy)
         }
         PyRTreeRef::Float64(tree) => {
             let boxes = tree
                 .boxes_at_level(level)
                 .map_err(|err| PyIndexError::new_err(err.to_string()))?;
-            boxes_to_arrow::<Float64Type>(boxes, tree.buffer().clone())
+            boxes_to_arrow::<Float64Type>(boxes, tree.buffer().clone(), copy)
         }
     };
     PyArray::from_array_ref(array).to_arro3(py)

python/src/rtree/partitions.rs

@@ -15,15 +15,26 @@ use crate::rtree::input::PyRTreeRef;
 use crate::util::slice_to_arrow;
 
 #[pyfunction]
-pub fn partitions(py: Python, index: PyRTreeRef) -> PyResult<PyObject> {
+#[pyo3(signature = (index, *, copy = false))]
+pub fn partitions(py: Python, index: PyRTreeRef, copy: bool) -> PyResult<PyObject> {
     let (indices, partition_ids) = match index {
         PyRTreeRef::Float32(tree) => {
-            let indices = indices_to_arrow(tree.indices(), tree.num_items(), tree.buffer().clone());
+            let indices = indices_to_arrow(
+                tree.indices(),
+                tree.num_items(),
+                tree.buffer().clone(),
+                copy,
+            );
             let partition_ids = partition_id_array(tree.num_items(), tree.node_size());
             (indices, partition_ids)
         }
         PyRTreeRef::Float64(tree) => {
-            let indices = indices_to_arrow(tree.indices(), tree.num_items(), tree.buffer().clone());
+            let indices = indices_to_arrow(
+                tree.indices(),
+                tree.num_items(),
+                tree.buffer().clone(),
+                copy,
+            );
             let partition_ids = partition_id_array(tree.num_items(), tree.node_size());
             (indices, partition_ids)
         }
@@ -38,10 +49,19 @@ pub fn partitions(py: Python, index: PyRTreeRef) -> PyResult<PyObject> {
         .to_arro3(py)
 }
 
-fn indices_to_arrow(indices: Indices, num_items: u32, owner: Arc<dyn Allocation>) -> ArrayRef {
+fn indices_to_arrow(
+    indices: Indices,
+    num_items: u32,
+    owner: Arc<dyn Allocation>,
+    copy: bool,
+) -> ArrayRef {
     match indices {
-        Indices::U16(slice) => slice_to_arrow::<UInt16Type>(&slice[0..num_items as usize], owner),
-        Indices::U32(slice) => slice_to_arrow::<UInt32Type>(&slice[0..num_items as usize], owner),
+        Indices::U16(slice) => {
+            slice_to_arrow::<UInt16Type>(&slice[0..num_items as usize], owner, copy)
+        }
+        Indices::U32(slice) => {
+            slice_to_arrow::<UInt32Type>(&slice[0..num_items as usize], owner, copy)
+        }
     }
 }
 
@@ -83,8 +103,9 @@ fn partition_id_array(num_items: u32, node_size: u16) -> ArrayRef {
 // Since for now we assume that the partition level is the node level, we select the boxes at level
 // 1.
 #[pyfunction]
-pub fn partition_boxes(py: Python, index: PyRTreeRef) -> PyResult<PyObject> {
-    let array = boxes_at_level(py, index, 1)?.extract::<PyArray>(py)?;
+#[pyo3(signature = (index, *, copy = false))]
+pub fn partition_boxes(py: Python, index: PyRTreeRef, copy: bool) -> PyResult<PyObject> {
+    let array = boxes_at_level(py, index, 1, copy)?.extract::<PyArray>(py)?;
     let (array, _field) = array.into_inner();
 
     let partition_ids: ArrayRef = if array.len() < u16::MAX as _ {

python/src/util.rs

@@ -10,25 +10,34 @@ use arrow_schema::Field;
 pub(crate) fn slice_to_arrow<T: ArrowPrimitiveType>(
     slice: &[T::Native],
     owner: Arc<dyn Allocation>,
+    copy: bool,
 ) -> ArrayRef {
-    let ptr = NonNull::new(slice.as_ptr() as *mut _).unwrap();
-    let len = slice.len();
-    let bytes_len = len * T::Native::get_byte_width();
+    if copy {
+        Arc::new(PrimitiveArray::<T>::new(
+            ScalarBuffer::from(slice.to_vec()),
+            None,
+        ))
+    } else {
+        let ptr = NonNull::new(slice.as_ptr() as *mut _).unwrap();
+        let len = slice.len();
+        let bytes_len = len * T::Native::get_byte_width();
 
-    // Safety:
-    // ptr is a non-null pointer owned by the RTree, which is passed in as the Allocation
-    let buffer = unsafe { Buffer::from_custom_allocation(ptr, bytes_len, owner) };
-    Arc::new(PrimitiveArray::<T>::new(
-        ScalarBuffer::new(buffer, 0, len),
-        None,
-    ))
+        // Safety:
+        // ptr is a non-null pointer owned by the RTree, which is passed in as the Allocation
+        let buffer = unsafe { Buffer::from_custom_allocation(ptr, bytes_len, owner) };
+        Arc::new(PrimitiveArray::<T>::new(
+            ScalarBuffer::new(buffer, 0, len),
+            None,
+        ))
+    }
 }
 
 pub(crate) fn boxes_to_arrow<T: ArrowPrimitiveType>(
     slice: &[T::Native],
     owner: Arc<dyn Allocation>,
+    copy: bool,
 ) -> ArrayRef {
-    let values_array = slice_to_arrow::<T>(slice, owner);
+    let values_array = slice_to_arrow::<T>(slice, owner, copy);
     Arc::new(FixedSizeListArray::new(
         Arc::new(Field::new("item", values_array.data_type().clone(), false)),
         4,