find the variance of all values in a map in rust

Here's how to find the variance of all values in a map in Rust:

main.rs
use std::collections::HashMap;
use statrs::statistics::Variance;

fn main() {
    let mut map = HashMap::new();
    map.insert("a", 1);
    map.insert("b", 2);
    map.insert("c", 3);
    map.insert("d", 4);
    map.insert("e", 5);

    let values: Vec<f64> = map.values().map(|value| *value as f64).collect();
    let variance = Variance::new_unbiased(&values).unwrap();

    println!("Variance: {}", variance);
}
415 chars
17 lines

In this code block, we are creating a new HashMap map, and inserting integer values into it. To find the variance of all the values in the map, we first convert them to a Vec<f64> using .values().map().

Next, we calculate the variance of the Vec<f64> using Variance::new_unbiased(). The new_unbiased() function creates a new unbiased variance estimator using the given data. If any data is missing, it will return an error.

Finally, we print the variance to the console using println!().