Distributions

Strafe provides a number of statistical distributions from R's base, and these distributions can be used to perform comparisons, calculations, and tests. Internally strafe uses these distributions for virtually all its calculations. Each distribution accepts numerics for its arguments (f64, i32, usize, etc.) and checks that these arguments are valid via the Constraint types. For example, the NormalBuilder accepts a mean that is Real (any number that is not a NAN), and a standard deviation that is Positive (any number that is greater than 0 and not NAN). You can find these constraint types in the strafe-type crate.

Below is an example of using the normal distribution to find the upper and lower 75th quantile, and 11 densities between -5 and 5.

use strafe::distribution::{Distribution, NormalBuilder};  
use strafe::types::FloatConstraint;  
  
fn main() {  
    let norm = NormalBuilder::new()  
        .with_mean(0)  
        .with_standard_deviation(1)  
        .build();  
    let lower = norm.quantile(0.95, false);  
    let upper = norm.quantile(0.95, true);  
    println!("{lower} {upper}");  
  
    let densities = (-5..=5)  
        .map(|x| norm.density(x as f64 / 5.0).unwrap())  
        .collect::<Vec<_>>();  
    println!("{densities:#.7?}");  
}

-1.6448536269514715 1.6448536269514715
[
    0.2419707,
    0.2896916,
    0.3332246,
    0.3682701,
    0.3910427,
    0.3989423,
    0.3910427,
    0.3682701,
    0.3332246,
    0.2896916,
    0.2419707,
]