Binary predicate for determining equivalence of two elements.
The input range to iterate over.
A range of elements of type Tuple!(ElementType!R, uint), representing each consecutively unique element and its respective number of occurrences in that run. This will be an input range if R is an input range, and a forward range in all other cases.
1 import std.algorithm.comparison : equal; 2 import std.typecons : tuple, Tuple; 3 4 int[] arr = [ 1, 2, 2, 2, 2, 3, 4, 4, 4, 5 ]; 5 assert(equal(group(arr), [ tuple(1, 1u), tuple(2, 4u), tuple(3, 1u), 6 tuple(4, 3u), tuple(5, 1u) ][]));
Using group, an associative array can be easily generated with the count of each unique element in the range.
1 import std.algorithm.sorting : sort; 2 import std.array : assocArray; 3 4 uint[string] result; 5 auto range = ["a", "b", "a", "c", "b", "c", "c", "d", "e"]; 6 result = range.sort!((a, b) => a < b) 7 .group 8 .assocArray; 9 10 assert(result == ["a": 2U, "b": 2U, "c": 3U, "d": 1U, "e": 1U]);
chunkBy, which chunks an input range into subranges of equivalent adjacent elements.
Groups consecutively equivalent elements into a single tuple of the element and the number of its repetitions.
Similarly to uniq, group produces a range that iterates over unique consecutive elements of the given range. Each element of this range is a tuple of the element and the number of times it is repeated in the original range. Equivalence of elements is assessed by using the predicate pred, which defaults to "a == b". The predicate is passed to std.functional.binaryFun, and can either accept a string, or any callable that can be executed via pred(element, element).