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class Array
# A utility method to return those elements in an array where the item in a
# corresponding array in true (matching by index)
def values_matching(a)
return [] unless a.respond_to?(:[])
result = []
each_with_index { |x, i| result << x if a[i] }
result
end
# Returns the smallest, i.e. least, non-nil element (can be used for any
# type of object that supports the <=> operator, including dates)
def smallest
# self.compact.sort.first
self.compact.min
end
# Returns the biggest, i.e. greatest, non-nil element
def biggest
# self.compact.sort.last
self.compact.max
end
# Flattens range objects within an array to allow include? to work within
# the array and within the ranges within the array.
def ranges_include?(value)
any? { |range| Array(range).include?(value) }
end
# Finds all the permutations of the array:
#
# [1,2,3].permutations #=> [1,2,3], [1,3,2], [2,1,3], [2,3,1], [3,1,2], [3,2,1]
# [3,3].permutations #=> [3,3], [3,3]
#
def permutations
return [self] if length == 1
orders = []
positions = (0...length).to_a
# Finding the permutations with a basic array of digits
positions.each do |position|
(positions - [position]).permutations.each do |permutation|
orders << permutation.unshift(position)
end
end
# We subsitute in our original elements. This prevents duplicate
# elements from causing problems, and allows the [3,3] example to work.
orders.map { |order| order.map { |index| self[index] } }
end
end
Version data entries
41 entries across 41 versions & 1 rubygems