1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
|
#![cfg(feature = "use_std")]
use std::collections::HashMap;
use std::hash::Hash;
use std::iter::Iterator;
/// Return a `HashMap` of keys mapped to a list of their corresponding values.
///
/// See [`.into_group_map()`](crate::Itertools::into_group_map)
/// for more information.
pub fn into_group_map<I, K, V>(iter: I) -> HashMap<K, Vec<V>>
where I: Iterator<Item=(K, V)>,
K: Hash + Eq,
{
let mut lookup = HashMap::new();
iter.for_each(|(key, val)| {
lookup.entry(key).or_insert_with(Vec::new).push(val);
});
lookup
}
pub fn into_group_map_by<I, K, V>(iter: I, f: impl Fn(&V) -> K) -> HashMap<K, Vec<V>>
where
I: Iterator<Item=V>,
K: Hash + Eq,
{
into_group_map(
iter.map(|v| (f(&v), v))
)
}
|
