group_by

Groups the elements of items by the key returned by key.

Within each group, elements keep their original order. The order of the groups themselves is unspecified (HashMap).

Import

use helpers4::array::group_by;

Cargo feature array (enabled by default). To compile only this module:

cargo add helpers4 --no-default-features --features array

or in Cargo.toml:

[dependencies]
helpers4 = { version = "0.0.5", default-features = false, features = ["array"] }

Signature

pub fn group_by<T: Clone, K: Eq + Hash>(
    items: &[T],
    mut key: impl FnMut(&T) -> K,
) -> HashMap<K, Vec<T>>

Parameters

Parameter	Type	Description
items	&[T]	The elements to group.
key	impl FnMut(&T) -> K	Returns the key to group each element under.

Returns

HashMap<K, Vec<T>>

Examples

use helpers4::array::group_by;

let groups = group_by(&[1, 2, 3, 4, 5], |n| n % 2 == 0);
assert_eq!(groups[&true], vec![2, 4]);
assert_eq!(groups[&false], vec![1, 3, 5]);

Source

src/array/group_by.rs