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Contents
class Array
# Returns a random subset of an Array. If a _number_
# of elements is specified then returns that number of
# elements, otherwise returns a random number of elements
# upto the size of the Array.
#
# By defualt the returned values are exclusive of
# each other, but if _exclusive_ is set to <tt>false</tt>,
# the same values can be choosen more than once.
#
# When _exclusive_ is <tt>true</tt> (the default) and the
# _number_ given is greater than the size of the array,
# then all values are returned.
#
# [1, 2, 3, 4].rand_subset(1) #=> [2]
# [1, 2, 3, 4].rand_subset(4) #=> [2, 1, 3, 4]
# [1, 2, 3, 4].rand_subset #=> [1, 3, 4]
# [1, 2, 3, 4].rand_subset #=> [2, 3]
#
def rand_subset( number=nil, exclusive=true )
number = rand( size ) unless number
number = number.to_int
#return self.dup if (number >= size and exlusive)
return sort_by{rand}.slice(0,number) if exclusive
ri =[]; number.times { |n| ri << rand( size ) }
return values_at(*ri)
end
end
# _____ _
# |_ _|__ ___| |_
# | |/ _ \/ __| __|
# | | __/\__ \ |_
# |_|\___||___/\__|
#
=begin test
require 'test/unit'
class TCArray < Test::Unit::TestCase
def test_rand_subset
10.times {
a = [1,2,3,4].rand_subset
assert( a.size <= 4 )
}
end
end
=end
Version data entries
26 entries across 26 versions & 1 rubygems