Top N Set

This crate provides a topset which selects a given number of greatest items. The criterium used to sort the items could be specified as a closure. It is based internally on a binary heap with a fixed size.

The struct TopSet could be used directly or through the trait TopSetReducing which automatically extend the iterator trait.

Note: the returned items are unsorted.

use topset::TopIter;


fn main()
{
    let items = vec![4, 5, 8, 3, 2, 1, 4, 7, 9, 8];
    
    // getting the four greatest integers (repeating allowed)
    items.iter().cloned()
            .topset(4, i32::gt)
            .into_iter()
            .for_each(|x| eprintln!("in the top 4: {}", x));

    // getting the four smallest integers
    // (we just need to reverse the comparison function)
    items.topset(4, i32::lt)
            .into_iter()
            .for_each(|x| eprintln!("in the last 4: {}", x));
}

will produce (possibly in a different order):

in the top 4: 7
in the top 4: 8
in the top 4: 9
in the top 4: 8
in the last 4: 4
in the last 4: 3
in the last 4: 1
in the last 4: 2