Calculates the average of a numeric collection.
@param default [Object] an optional default return value if there are no elements.
It's nil by default.
@return The average of the elements or the default value if there are no
elements.
@example
[1, 2, 3].average #=> 2 [1, 2, 3, 4].average #=> 2.5 [].average #=> nil [].average(0) #=> 0
Drops the last n elements of an enumerable.
@param n [Fixnum] the number of elements to drop @return [Array] an array containing the remaining elements
@example
[1, 2, 3].drop_last(1) #=> [1, 2] [].drop_last(5) #=> []
Drops the last elements of an enumerable meeting a predicate.
@return [Array] an array containing the remaining elements
@example
[1, 2, 3].drop_last_while(&:odd?) #=> [1, 2]
Checks if exactly n elements meet a certain predicate.
@param n [Fixnum] the number of matches required @return [Boolean] true if we get exactly n matches, false otherwise
@example
[1, 2, 3, 4].exactly?(1) { |n| n > 3 } #=> true [1, 2, 3, 4].exactly?(2, &:even?) #=> true [1, 1, 3, 3].exactly?(2, &:even?) #=> false
Without a block uses the identify of the elements as default predicate. This means that nil and false elements will be ignored.
@example
[1, false, nil].exactly?(3) #=> false [1, false, nil].exactly?(1) #=> true [false, nil].exactly?(0) #=> true [1, 2, 3].exactly?(3) #=>true
Counts the number of occurrence of items in the enumerable.
@return [Hash] in the format value => count
@example
[].frequencies # => {} [1, :symbol, 'string', 3, :symbol, 1].frequencies #=> { 1 => 2, :symbol => 2, 'string' => 1, 3 => 1 }
Checks if two or more elements meet a certain predicate.
@example
[1, 2, 3, 4].several?(&:even?) #=> true [1, 1, 3, 3].several?(&:even?) #=> false
Without a block uses the identify of the elements as default predicate. This means that nil and false elements will be ignored.
@example
[1, false, nil].several? #=> false [1, 2, 3].several? #=>true
Sums up elements of a collection by invoking their `+` method. Most useful for summing up numbers.
@param initial [Object] an optional initial value.
It defaults to 0 for an empty collection.
@return The sum of the elements, or the initial value if there
are no elements.
@example
[1, 2, 3].sum #=> 6 [[1], [2], [3]].sum #=> [1, 2, 3] [].sum #=> 0 ["a"].sum #=> "a" ["b", "c"].sum("a") #=> "abc"
Take the last n elements of an enumerable.
@param n [Fixnum] the number of elements to take @return [Array] an array containing the requested elements
@example
[1, 2, 3].take_last(2) #=> [2, 3] [].take_last(5) #=> []
Take the last n elements of an enumerable meeting a certain predicate.
@return [Array] an array containing the matching elements
@example
[1, 2, 3, 5].take_last_while(&:odd?) #=> [3, 5]