Crate ndarrow 

ndarrow

Zero-copy bridge between Apache Arrow and ndarray.

ndarrow lets you move data between Arrow and ndarray with zero allocations on the bridge path:

• Arrow → ndarray: borrow Arrow buffers as ndarray views (O(1), no copy)
• ndarray → Arrow: transfer owned ndarray buffers into Arrow arrays (O(1), ownership move)

Quick Example

use arrow_array::Float64Array;
use ndarrow::{AsNdarray, IntoArrow};
use ndarray::Array1;

// Arrow -> ndarray (zero-copy view)
let arrow_array = Float64Array::from(vec![1.0, 2.0, 3.0, 4.0]);
let view = arrow_array.as_ndarray().unwrap(); // ArrayView1<f64>, no allocation
assert_eq!(view[0], 1.0);

// ndarray -> Arrow (zero-copy ownership transfer)
let result = Array1::from_vec(vec![5.0, 6.0, 7.0, 8.0]);
let arrow_result: Float64Array = result.into_arrow().unwrap();
assert_eq!(arrow_result.len(), 4);

Null Handling

Null semantics are explicit at the call site:

use arrow_array::Float64Array;
use ndarrow::AsNdarray;

let array = Float64Array::from(vec![1.0, 2.0, 3.0]);

// Validated: returns Err if nulls present (O(1) check)
let view = array.as_ndarray().unwrap();

// Unchecked: caller guarantees no nulls (zero cost)
let view = unsafe { array.as_ndarray_unchecked() };

// Masked: returns view + validity bitmap (zero allocation)
let (view, mask) = array.as_ndarray_masked();

Performance Guarantee

Bridge conversions are O(1) regardless of array size. The bridge creates views (pointer + shape) or transfers buffer ownership. It never touches the data.

Re-exports

pub use complex::Complex32Extension;

pub use complex::Complex64Extension;

pub use complex::array1_complex32_to_extension;

pub use complex::array1_complex64_to_extension;

pub use complex::complex32_as_array_view1;

pub use complex::complex64_as_array_view1;

pub use element::NdarrowElement;

pub use error::NdarrowError;

pub use extensions::RegisteredExtension;

pub use extensions::deserialize_registered_extension;

pub use extensions::registered_extension_names;

pub use inbound::AsNdarray;

pub use inbound::fixed_size_list_as_array2;

pub use inbound::fixed_size_list_as_array2_masked;

pub use inbound::fixed_size_list_as_array2_unchecked;

pub use outbound::IntoArrow;

pub use sparse::CsrMatrixExtension;

pub use sparse::CsrMatrixMetadata;

pub use sparse::CsrView;

pub use sparse::csr_to_extension_array;

pub use sparse::csr_view_from_columns;

pub use sparse::csr_view_from_extension;

pub use tensor::VariableShapeTensorIter;

pub use tensor::arrayd_to_fixed_shape_tensor;

pub use tensor::arrays_to_variable_shape_tensor;

pub use tensor::fixed_shape_tensor_as_array_viewd;

pub use tensor::variable_shape_tensor_iter;

Modules

complex

Complex-valued Arrow/ndarray bridge utilities.

element

Element type bridge between Arrow primitive types and ndarray element types.

error

Error types for ndarrow conversions.

extensions

Extension type registration and deserialization utilities.

helpers

Explicit helper APIs that may allocate.

inbound

Arrow to ndarray conversions (zero-copy views).

outbound

ndarray to Arrow conversions (zero-copy ownership transfer).

prelude

ndarrow prelude.

sparse

Sparse Arrow/ndarray bridge utilities.

tensor

Tensor Arrow/ndarray bridge utilities.