Class: Array

Return a new array that is an arrangement of self based on the indices in the array that is passed as parameter.

# File permutations.rb, line 76
        def arrange(a)
                return nil if a.length != self.length or a.any? {|x| x < 0 or x >= self.length}
                ret = []
                0.upto(self.length - 1) {|i| ret[i] = self[a[i]] }
                ret
        end

combinations(k) {|self.select_indices(a) }| ...}

Generate the sequence of combinations taken k at a time for this Array. Return the number of such combinations. Return nil if the parameter is invalid. If no block is given, the sequence is not actually generated.

[Source]

# File combinations.rb, line 72
        def combinations(k)
                c = Combinations.new(self.length, k)
                if block_given?
                        c.each { |a| yield self.select_indices(a) }
                else
                        c.each
                end
        end

permutations() {|self.arrange(a) }| ...}

Yield a sequence of all permutations of self. Return the number of permutations.

[Source]

# File permutations.rb, line 83
        def permutations
                p = Permutations.new(self.length)
                if block_given?
                        p.each {|a| yield self.arrange(a) }
                else
                        p.each
                end
        end

rotate!()

Rotate self by moving the first element of the array to the end.

[Source]

# File permutations.rb, line 71
        def rotate!
                self << self.shift
        end

select_indices(a)

Return a new Array that is formed by selecting the indices given in the parameter. Return nil if any of the indices are out of range.

[Source]

# File combinations.rb, line 82
        def select_indices(a)
                return nil if a.length > self.length or a.any? {|x| x < 0 or x >= self.length}
                ret = []
                a.each {|i| ret << self[i] }
                ret
        end

sequence(lo, hi)

Append the numbers lo..hi to the array.

[Source]

# File combinations.rb, line 65
        def sequence(lo, hi)
                lo.upto(hi) { |i| self << i }
                self
        end

Methods

Public Instance methods