array

Helpers for slices and Vecs that the standard library does not provide.

Inputs are borrowed slices and results are new Vecs: nothing is mutated. Membership-based helpers require Eq + Hash. Shuffling and sampling live in the random module, where the generator is an argument.

Install

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 = "0.0.11", default-features = false, features = ["array"] }

Import path: helpers4::array.

Items

Item	What it does
cartesian_product	Returns every pair (x, y) with x from a and y from b, in row-major order.
count_by	Counts the elements of items per key returned by key.
difference	Returns the elements of a that are not in b, in a’s order.
duplicates	Returns the elements that appear more than once in items, each one once, in the order they first appear.
equals_unordered	Returns true when a and b hold the same elements the same number of times, in any order.
group_by	Groups the elements of items by the key returned by key.
interleave	Alternates the elements of a and b, starting with a; the leftover of the longer slice goes at the end.
intersection	Returns the elements of a that also appear in b, in a’s order.
intersects	Returns true when a and b share at least one element.
key_by	Indexes the elements of items by the key returned by key.
replace_or_append	Replaces the first element that matches with item, or appends item when none does: the “upsert into a list” gesture.
symmetric_difference	Returns the elements present in exactly one of a and b.
toggle	Removes item from items if it is there, adds it at the end if it is not: the usual “toggle a selection” gesture.
toggle_by	Like toggle, but elements are the same when key gives the same value: toggle objects by id instead of by whole-value equality.
unique	Removes duplicate values, keeping the first occurrence of each and the original order.
unique_by	Removes elements whose key was already seen, keeping the first of each key in order.