Struct vose_alias::VoseAlias

pub struct VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug,  {
    pub elements: Vec<T>,
    pub alias: HashMap<T, T>,
    pub prob: HashMap<T, f32>,
    // some fields omitted
}

A structure containing the necessary Vose-Alias tables.

The structure contains the following attributes:

1. A vector containing the elements to sample frmo
2. The Alias table, created from the Vose-Alias initialization step
3. The Probability table, created frmo the Vose-Alias initialization step

The structure is created by the function vose_alias::new(). See its documentation for more details.

Internally, the elements are used as indexes in HashMap and Vec. Therefore, the type T must implement the following traits:

• Copy
• Hash
• Eq
• Debug

Fields

elements: Vec<T>

alias: HashMap<T, T>

prob: HashMap<T, f32>

Implementations

impl<T> VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

pub fn new(element_vector: Vec<T>, probability_vector: Vec<f32>) -> VoseAlias<T>

Returns the Vose-Alias object containing the element vector as well as the alias and probability tables.

The element_vector contains the list of elements that should be sampled from. The probability_vector contains the probability distribution to be sampled with. element_vector and probability_vector should have the same size and probability_vector should describe a well-formed probability distribution.

Panics

The function panics in two casese:

1. the element_vector and the probability_vector do not contain the same number of elements
2. the sum of the elements in probability_vector is not equal to 1 (with a floating number precision of 0.0001), meaning that probability_vector does not describe a well formed probability distribution

Examples

use vose_alias::VoseAlias;
 
// Creates a Vose-Alias object from a list of Integer elements
let va = VoseAlias::new(vec![1, 2, 3, 4], vec![0.5, 0.2, 0.2, 0.1]);

pub fn sample(&self) -> T

Returns a sampled element from a previously created Vose-Alias object.

This function uses a VoseAlias object previously created using the method vose_alias::new() to sample in linear time an element of type T.

Panics

This function panics only if the lists created in vose_alias::new() are not correctly form, which would indicate a internal bug in the code. If your code panics while using this function, please fill in an issue report.

Examples

use vose_alias::VoseAlias;

// Samples an integer from a list and prints it. 
let va = VoseAlias::new(vec![1, 2, 3, 4], vec![0.5, 0.2, 0.2, 0.1]);
let element = va.sample();
println!("{}", element);
 

Trait Implementations

impl<T: Clone> Clone for VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

fn clone(&self) -> VoseAlias<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Display for VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Eq for VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

impl<T> PartialEq<VoseAlias<T>> for VoseAlias<T> where
    T: Display + Copy + Hash + Eq + Debug, 

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]fn ne(&self, other: &Rhs) -> bool

This method tests for !=.