map { |item| block } → new_ary map → Enumerator Invokes the given block once for each element of self. Creates a new array containing the values returned by the block. See also Enumerable#collect. If no block is given, an Enumerator is returned instead. ex. a = [ "a", "b", "c", "d" ] a.collect { |x| x + "!" } #=> ["a!", "b!", "c!", "d!"] a.map.with_index{ |x, i| x * i } #=> ["", "b", "cc", "ddd"] a #=> ["a", "b", "c", "d"]

group_by { |obj| block } → a_hash group_by → an_enumerator Groups the collection by result of the block. Returns a hash where the keys are the evaluated result from the block and the values are arrays of elements in the collection that correspond to the key. If no block is given an enumerator is returned. ex. (1..6).group_by { |i| i%3 } #=> {0=>[3, 6], 1=>[1, 4], 2=>[2, 5]}

cycle(n=nil) { |obj| block } → nil cycle(n=nil) → an_enumerator Calls block for each element of enum repeatedly n times or forever if none or nil is given. If a non-positive number is given or the collection is empty, does nothing. Returns nil if the loop has finished without getting interrupted. #cycle saves elements in an internal array so changes to enum after the first pass have no effect. If no block is given, an enumerator is returned instead. a = ["a", "b", "c"] a.cycle { |x| puts x } # print, a, b, c, a, b, c,.. forever. a.cycle(2) { |x| puts x } # print, a, b, c, a, b, c.