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unless Array.method_defined? :sample
require 'backports/tools/arguments'
class Array
def sample(n = Backports::Undefined, options = Backports::Undefined)
if options == Backports::Undefined && n.respond_to?(:to_hash)
n, options = options, n
end
rng = Backports.coerce_to_option(options, :random) unless options == Backports::Undefined
generator = if rng.respond_to? :rand
Proc.new do |nb|
r = Backports::coerce_to_int(rng.rand(nb))
raise RangeError, "random generator returned #{r} which is not in 0...#{nb}" if r < 0 || r >= nb
r
end
else
Kernel.method(:rand)
end
return self[generator.call(size)] if n == Backports::Undefined
n = Backports.coerce_to_int(n)
raise ArgumentError, "negative array size" if n < 0
n = size if n > size
result = Array.new(self)
n.times do |i|
r = i + generator.call(size - i)
result[i], result[r] = result[r], result[i]
end
result[n..size] = []
result
end
end
end
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