Question

How to calculate the mean and the standard deviation of a vector of floating-point values in Rust

Answer 1

fn main() {
    let numbers = vec![3.4, 1.8, 4.3, 5.0, 6.2];

    let mean = calculate_mean(&numbers);
    let stddev = calculate_standard_deviation(&numbers, mean);

    println!("Mean: {:.2}", mean);
    println!("Standard Deviation: {:.2}", stddev);
}

fn calculate_mean(data: &[f64]) -> f64 {
    if data.is_empty() {
        return 0.0;
    }

    let sum: f64 = data.iter().sum();

    sum / data.len() as f64
}

fn calculate_standard_deviation(data: &[f64], mean: f64) -> f64 {
    let n = data.len();
    if n < 2 {
        return 0.0;
    }

    let sum_of_squared_differences: f64 = data
        .iter()
        .map(|value| {
            let diff = value - mean;
            diff * diff
        })
        .sum();

    let variance = sum_of_squared_differences / (n as f64 - 1.0);

    variance.sqrt()
}

 
 
/*
run:
   
Mean: 4.14
Standard Deviation: 1.66
   
*/
 

 

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