Function index 

pub fn index<'a, T, K, F>(data: &'a [T], key: F) -> HashMap<K, &'a T>
where
    K: Eq + Hash,
    F: Fn(&T) -> K,

Creates an index from key to element.

If multiple elements have the same key, the last one wins.

Example

use d3rs::array::index;

let data = vec![
    ("id1", "Alice"),
    ("id2", "Bob"),
    ("id3", "Charlie"),
];

let indexed = index(&data, |item| item.0);
assert_eq!(indexed[&"id2"].1, "Bob");