如何生成介于0和n之间的随机数?
当前回答
也许这对你有帮助。我在应用程序中使用此功能
https://github.com/rubyworks/facets
class String
# Create a random String of given length, using given character set
#
# Character set is an Array which can contain Ranges, Arrays, Characters
#
# Examples
#
# String.random
# => "D9DxFIaqR3dr8Ct1AfmFxHxqGsmA4Oz3"
#
# String.random(10)
# => "t8BIna341S"
#
# String.random(10, ['a'..'z'])
# => "nstpvixfri"
#
# String.random(10, ['0'..'9'] )
# => "0982541042"
#
# String.random(10, ['0'..'9','A'..'F'] )
# => "3EBF48AD3D"
#
# BASE64_CHAR_SET = ["A".."Z", "a".."z", "0".."9", '_', '-']
# String.random(10, BASE64_CHAR_SET)
# => "xM_1t3qcNn"
#
# SPECIAL_CHARS = ["!", "@", "#", "$", "%", "^", "&", "*", "(", ")", "-", "_", "=", "+", "|", "/", "?", ".", ",", ";", ":", "~", "`", "[", "]", "{", "}", "<", ">"]
# BASE91_CHAR_SET = ["A".."Z", "a".."z", "0".."9", SPECIAL_CHARS]
# String.random(10, BASE91_CHAR_SET)
# => "S(Z]z,J{v;"
#
# CREDIT: Tilo Sloboda
#
# SEE: https://gist.github.com/tilo/3ee8d94871d30416feba
#
# TODO: Move to random.rb in standard library?
def self.random(len=32, character_set = ["A".."Z", "a".."z", "0".."9"])
chars = character_set.map{|x| x.is_a?(Range) ? x.to_a : x }.flatten
Array.new(len){ chars.sample }.join
end
end
https://github.com/rubyworks/facets/blob/5569b03b4c6fd25897444a266ffe25872284be2b/lib/core/facets/string/random.rb
这对我来说很好
其他回答
别忘了先用srand()为RNG种子。
这个呢?
n = 3
(0..n).to_a.sample
也许这对你有帮助。我在应用程序中使用此功能
https://github.com/rubyworks/facets
class String
# Create a random String of given length, using given character set
#
# Character set is an Array which can contain Ranges, Arrays, Characters
#
# Examples
#
# String.random
# => "D9DxFIaqR3dr8Ct1AfmFxHxqGsmA4Oz3"
#
# String.random(10)
# => "t8BIna341S"
#
# String.random(10, ['a'..'z'])
# => "nstpvixfri"
#
# String.random(10, ['0'..'9'] )
# => "0982541042"
#
# String.random(10, ['0'..'9','A'..'F'] )
# => "3EBF48AD3D"
#
# BASE64_CHAR_SET = ["A".."Z", "a".."z", "0".."9", '_', '-']
# String.random(10, BASE64_CHAR_SET)
# => "xM_1t3qcNn"
#
# SPECIAL_CHARS = ["!", "@", "#", "$", "%", "^", "&", "*", "(", ")", "-", "_", "=", "+", "|", "/", "?", ".", ",", ";", ":", "~", "`", "[", "]", "{", "}", "<", ">"]
# BASE91_CHAR_SET = ["A".."Z", "a".."z", "0".."9", SPECIAL_CHARS]
# String.random(10, BASE91_CHAR_SET)
# => "S(Z]z,J{v;"
#
# CREDIT: Tilo Sloboda
#
# SEE: https://gist.github.com/tilo/3ee8d94871d30416feba
#
# TODO: Move to random.rb in standard library?
def self.random(len=32, character_set = ["A".."Z", "a".."z", "0".."9"])
chars = character_set.map{|x| x.is_a?(Range) ? x.to_a : x }.flatten
Array.new(len){ chars.sample }.join
end
end
https://github.com/rubyworks/facets/blob/5569b03b4c6fd25897444a266ffe25872284be2b/lib/core/facets/string/random.rb
这对我来说很好
尝试array#shuffle方法进行随机化
array = (1..10).to_a
array.shuffle.first
虽然您可以使用rand(42-10)+10来获得10到42之间的随机数(其中10是包含的,42是不包含的),但自Ruby 1.9.3以来,有一种更好的方法,您可以调用:
rand(10...42) # => 13
通过需要我的backports gem,可用于所有版本的Ruby。
Ruby1.9.2还引入了Random类,因此您可以创建自己的随机数生成器对象,并具有一个很好的API:
r = Random.new
r.rand(10...42) # => 22
r.bytes(3) # => "rnd"
Random类本身充当随机生成器,因此可以直接调用:
Random.rand(10...42) # => same as rand(10...42)
关于Random.new的注释
在大多数情况下,最简单的方法是使用rand或Random.rand。每次你想要一个随机数时,创建一个新的随机生成器是一个非常糟糕的主意。如果您这样做,您将获得初始种子算法的随机财产,与随机生成器本身的财产相比,这些属性非常糟糕。
如果您使用Random.new,那么应该尽可能少地调用它,例如,一次调用MyApp::Random=Random.nnew,并在其他地方使用它。
Random.new有帮助的情况如下:
您正在编写一个gem,不想干扰主程序可能依赖的rand/Random.rand序列您需要单独的可重复随机数序列(例如每个线程一个)您希望能够保存和恢复可复制的随机数序列(就像随机对象可以编组一样简单)
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