Narrow

An implementation of Apache Arrow.

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Minimum supported Rust version

The minimum supported Rust version is 1.56.1.

Example

Struct array

use narrow::{Array, BooleanArray, Float32Array, StructArray, Uint8Array};

#[derive(Array, Copy, Clone, Debug, PartialEq)]
pub struct Person {
    name: String,
    age: u8,
    happy: bool,
    distance: Option<f32>,
}

let persons = vec![
    Person {
        name: "A".to_string(),
        age: 20,
        happy: true,
        distance: Some(1.5),
    },
    Person {
        name: "B".to_string(),
        age: 22,
        happy: true,
        distance: None,
    },
];

// Convert array of structs to struct of arrays.
let persons_array: StructArray<Person, false> = persons.clone().into_iter().collect();
assert_eq!(persons_array.len(), 2);

// To sum the ages we only need to read the `age` array.
let age_array: &Uint8Array<false> = &persons_array.age;
assert_eq!(age_array.into_iter().sum::<u8>(), 42);

// Make sure everyone is happy.
let happy_array: &BooleanArray<false> = &persons_array.happy;
assert!(happy_array.into_iter().all(|bool| bool));

// The const generic bool in array types indicates nullability of the
// values in that array.
let distance_array: &Float32Array<true> = &persons_array.distance;
assert_eq!(distance_array.null_count(), 1);

// Convert struct of arrays back to array of structs
assert_eq!(persons_array.into_iter().collect::<Vec<_>>(), persons);

Union array

use narrow::{Array, UnionArray};

#[derive(Array, Copy, Clone, Debug, PartialEq)]
pub enum Either {
    This(bool),
    That(Option<u32>)
}

let input = vec![
    Either::This(false),
    Either::This(true),
    Either::That(Some(1234)),
    Either::That(None),
    Either::This(true)
];

let array: UnionArray<Either, true> = input.iter().copied().collect();

assert_eq!(array.len(), 5);
assert_eq!(array.child().This.len(), 3);
assert_eq!(array.child().That.len(), 2);
assert_eq!(array.child().That.null_count(), 1);

assert_eq!(array.into_iter().collect::<Vec<Either>>(), input);

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

teratide/narrow