Sha256: f6b2a675e0887ebd8a2984840baeb83736d55a8b0e05b12303396b02d0ecf0e3
Contents?: true
Size: 987 Bytes
Versions: 26
Compression:
Stored size: 987 Bytes
Contents
class Array
# Yields the block to each unique combination of _n_ elements.
#
# a = %w|a b c d|
# a.each_combination(3) do |c|
# p c
# end
#
# produces
#
# ["a", "b", "c"]
# ["a", "b", "d"]
# ["a", "c", "d"]
# ["b", "c", "d"]
#
def each_combination(k=2)
s = self.to_a
n = s.size
return unless (1..n) === k
idx = (0...k).to_a
loop do
yield s.values_at(*idx)
i = k - 1
i -= 1 while idx[i] == n - k + i
break if i < 0
idx[i] += 1
(i + 1 ... k).each {|j| idx[j] = idx[i] + j - i}
end
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCEnumerable < Test::Unit::TestCase
def test_each_combination
r = []
a = [1,2,3,4]
a.each_combination(2){ |a,b| r << [a,b] }
assert_equal( [[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]], r )
end
end
=end
Version data entries
26 entries across 26 versions & 1 rubygems