Trait RandomRefExt 

pub trait RandomRefExt<A, D>
where
    D: Dimension,
{
    // Required methods
    fn sample_axis(
        &self,
        axis: Axis,
        n_samples: usize,
        strategy: SamplingStrategy,
    ) -> Array<A, D>
       where A: Copy,
             D: RemoveAxis;
    fn sample_axis_using<R>(
        &self,
        axis: Axis,
        n_samples: usize,
        strategy: SamplingStrategy,
        rng: &mut R,
    ) -> Array<A, D>
       where R: Rng + ?Sized,
             A: Copy,
             D: RemoveAxis;
}

Extension trait for sampling from ArrayRef with random elements.

The default RNG is a fast, automatically seeded rng (currently rand::rngs::SmallRng, seeded from rand::rng).

Note that SmallRng is cheap to initialize and fast, but it may generate low-quality random numbers, and reproducibility is not guaranteed. See its documentation for information. You can select a different RNG with .sample_axis_using().

Required Methods

fn sample_axis( &self, axis: Axis, n_samples: usize, strategy: SamplingStrategy, ) -> Array<A, D>

where A: Copy, D: RemoveAxis,

Sample n_samples lanes slicing along axis using the default RNG.

If strategy==SamplingStrategy::WithoutReplacement, each lane can only be sampled once. If strategy==SamplingStrategy::WithReplacement, each lane can be sampled multiple times.

Panics when:

• creation of the RNG fails;
• n_samples is greater than the length of axis (if sampling without replacement);
• length of axis is 0.

use ndarray::{array, Axis};
use ndarray_rand::{RandomExt, SamplingStrategy};

let a = array![
    [1., 2., 3.],
    [4., 5., 6.],
    [7., 8., 9.],
    [10., 11., 12.],
];
// Sample 2 rows, without replacement
let sample_rows = a.sample_axis(Axis(0), 2, SamplingStrategy::WithoutReplacement);
println!("{:?}", sample_rows);
// Example Output: (1st and 3rd rows)
// [
//  [1., 2., 3.],
//  [7., 8., 9.]
// ]
// Sample 2 columns, with replacement
let sample_columns = a.sample_axis(Axis(1), 1, SamplingStrategy::WithReplacement);
println!("{:?}", sample_columns);
// Example Output: (2nd column, sampled twice)
// [
//  [2., 2.],
//  [5., 5.],
//  [8., 8.],
//  [11., 11.]
// ]

fn sample_axis_using<R>( &self, axis: Axis, n_samples: usize, strategy: SamplingStrategy, rng: &mut R, ) -> Array<A, D>

where R: Rng + ?Sized, A: Copy, D: RemoveAxis,

Sample n_samples lanes slicing along axis using the specified RNG rng.

If strategy==SamplingStrategy::WithoutReplacement, each lane can only be sampled once. If strategy==SamplingStrategy::WithReplacement, each lane can be sampled multiple times.

Panics when:

• creation of the RNG fails;
• n_samples is greater than the length of axis (if sampling without replacement);
• length of axis is 0.

use ndarray::{array, Axis};
use ndarray_rand::{RandomExt, SamplingStrategy};
use ndarray_rand::rand::SeedableRng;
use rand_isaac::isaac64::Isaac64Rng;

// Get a seeded random number generator for reproducibility (Isaac64 algorithm)
let seed = 42;
let mut rng = Isaac64Rng::seed_from_u64(seed);

let a = array![
    [1., 2., 3.],
    [4., 5., 6.],
    [7., 8., 9.],
    [10., 11., 12.],
];
// Sample 2 rows, without replacement
let sample_rows = a.sample_axis_using(Axis(0), 2, SamplingStrategy::WithoutReplacement, &mut rng);
println!("{:?}", sample_rows);
// Example Output: (1st and 3rd rows)
// [
//  [1., 2., 3.],
//  [7., 8., 9.]
// ]

// Sample 2 columns, with replacement
let sample_columns = a.sample_axis_using(Axis(1), 1, SamplingStrategy::WithReplacement, &mut rng);
println!("{:?}", sample_columns);
// Example Output: (2nd column, sampled twice)
// [
//  [2., 2.],
//  [5., 5.],
//  [8., 8.],
//  [11., 11.]
// ]

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl<A, D> RandomRefExt<A, D> for ArrayRef<A, D>

where D: Dimension,

fn sample_axis( &self, axis: Axis, n_samples: usize, strategy: SamplingStrategy, ) -> Array<A, D>

where A: Copy, D: RemoveAxis,

fn sample_axis_using<R>( &self, axis: Axis, n_samples: usize, strategy: SamplingStrategy, rng: &mut R, ) -> Array<A, D>

where R: Rng + ?Sized, A: Copy, D: RemoveAxis,

Implementors