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Contents
#--
# Credit goes to Niel Spring.
#++
class Array
# Randomize the order of an array.
#
# [1,2,3,4].shuffle #=> [2,4,1,3]
#
def shuffle
dup.shuffle!
#sort_by{Kernel.rand}
end
# As with #shuffle but modifies the array in place.
# The algorithm used here is known as a Fisher-Yates shuffle.
#
# a = [1,2,3,4]
# a.shuffle!
# a #=> [2,4,1,3]
#
def shuffle!
s = size
each_index do |j|
i = Kernel.rand(s-j)
#self[j], self[j+i] = self[j+i], self[j]
tmp = self[j]
self[j] = self[j+i]
self[j+i] = tmp
end
self
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCArray < Test::Unit::TestCase
def test_shuffle
a = [1,2,3,4,5]
b = a.shuffle
assert_equal( a, b.sort )
end
def test_shuffle!
a = [1,2,3,4,5]
b = a.dup
b.shuffle!
assert_equal( a, b.sort )
end
end
=end
Version data entries
26 entries across 26 versions & 1 rubygems