Created
July 26, 2008 03:04
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Array#Product For Ruby 1.8
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class Array | |
# Array#product | |
# ------------- | |
# Returns the cartesian product of the receiver and the arrays given as arguments. | |
# | |
# Usage: | |
# [1, 2, 3].product([4, 5]) # => [[1, 4], [1, 5], [2, 4], [2, 5], [3, 4], [3, 5]] | |
# [1, 2].product([1, 2]) # => [[1, 1], [1, 2], [2, 1], [2, 2]] | |
# [1, 2].product([3, 4],[5, 6]) # => [[1, 3, 5], [1, 3, 6], [1, 4, 5], [1, 4, 6], | |
# # [2, 3, 5], [2, 3, 6], [2, 4, 5], [2, 4, 6]] | |
# [1, 2].product() # => [[1], [2]] | |
# [1, 2].product([]) # => [] | |
# | |
# [1] * [2, 3] # => [[1, 2], [1, 3]] | |
# [1, 2] * [3, 4] # => [[1, 3], [1, 4], [2, 3], [2, 4]] | |
# | |
def product(*others) | |
arrays = [ self.map {|i| [i] } ].concat(others) | |
arrays.inject do |result, item| | |
(result * item).map do |t| | |
t[0].dup << t[1] | |
end | |
end | |
end | |
def multiplication_operator_with_product(other) | |
unless other.kind_of? Array | |
multiplication_operator_without_product(other) | |
else | |
self.inject([]) do |ret, i| | |
ret.concat( other.map {|j| [i, j]} ) | |
end | |
end | |
end | |
alias_method :multiplication_operator_without_product, :* | |
alias_method :*, :multiplication_operator_with_product | |
end |
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