Sha256: 0ad3388d1162f489f48c44a0a5f42b63a7fda7532160ea43f485b509221bfe3a
Contents?: true
Size: 834 Bytes
Versions: 7
Compression:
Stored size: 834 Bytes
Contents
class Array
unless method_defined?(:combination) # 1.8.7+
require 'facets/enumerator'
# Yields the block to each unique combination of _n_ elements.
#
# a = %w|a b c d|
# a.combination(3)
#
# produces
#
# [["a", "b", "c"],
# ["a", "b", "d"],
# ["a", "c", "d"],
# ["b", "c", "d"]]
#
# CREDIT: Florian Gross
def combination(k=2)
if block_given?
s = 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
else
to_enum(:combination, k)
end
end
end
end
Version data entries
7 entries across 6 versions & 1 rubygems