What is the idiomatic way to get the index of a maximum or minimum floating point value in a slice or Vec in Rust?

Question

Assumption -- The Vec does not have any NaN values or exhibit any NaN behavior.

T

Answer 1

I will probably do something like this:

fn main() -> Result<(), Box> {
    let samples = vec![
        0.28, 0.3102, 0.9856, 0.3679, 0.3697, 0.46, 0.4311, 0.9781, 0.9891, 0.5052, 0.9173, 0.932,
        0.8365, 0.5822, 0.9981, 0.9977,
    ];

    // Use enumerate to get the index
    let mut iter = samples.iter().enumerate();
    // we get the first entry
    let init = iter.next().ok_or("Need at least one input")?;
    // we process the rest
    let result = iter.try_fold(init, |acc, x| {
        // return None if x is NaN
        let cmp = x.1.partial_cmp(acc.1)?;
        // if x is greater the acc
        let max = if let std::cmp::Ordering::Greater = cmp {
            x
        } else {
            acc
        };
        Some(max)
    });
    println!("{:?}", result);

    Ok(())
}

This could be implemented by adding a trait on Iterator with for example the function try_max_by.