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.