如何从数组中随机选取?

I want to know if there is a much cleaner way of doing this. Basically, I want to pick a random element from an array of variable length. Normally, I would do it like this:

我想知道是否有更清洁的方法来做这件事。基本上，我想从一个可变长度的数组中选择一个随机的元素。通常我会这样做:

myArray = ["stuff", "widget", "ruby", "goodies", "java", "emerald", "etc" ]
item = myArray[rand(myarray.length)]

Is there something that is more readable / simpler to replace the second line? Or is that the best way to do it. I suppose you could do myArray.shuffle.first, but I only saw #shuffle a few minutes ago on SO, I haven't actually used it yet.

是否有什么东西更容易读/更容易替换第二行?或者这是最好的方法。我想你可以做我的。首先，但是我在几分钟前才看到#shuffle，我还没有实际使用它。

5 个解决方案

#1

Just use Array#sample:

只使用数组#样品:

[:foo, :bar].sample # => :foo, or :bar :-)

It is available in Ruby 1.9.1+. To be also able to use it with an earlier version of Ruby, you could require "backports/1.9.1/array/sample".

它可以在Ruby 1.9.1+中使用。为了能够使用Ruby的早期版本，您可能需要“backports/1.9.1/array/sample”。

Note that in Ruby 1.8.7 it exists under the unfortunate name choice; it was renamed in later version so you shouldn't use that.

请注意，在Ruby 1.8.7中，它存在于不幸的名称选择之下;它在以后的版本中被重新命名，所以你不应该使用它。

Although not useful in this case, sample accepts a number argument in case you want a number of distinct samples.

虽然在这种情况下不太有用，但是示例接受一个数字参数，以防您需要一些不同的示例。

#2

myArray.sample(x) can also help you to get x random elements from the array.

sample(x)也可以帮助您从数组中获取x随机元素。

#3

Random Number of Random Items from an Array

def random_items(array)
  array.sample(1 + rand(array.count))
end

---

Examples of possible results:

my_array = ["one", "two", "three"]
my_array.sample(1 + rand(my_array.count))

=> ["two", "three"]
=> ["one", "three", "two"]
=> ["two"]

#4

myArray.sample

will return 1 random value.

将返回1个随机值。

myArray.shuffle.first

will also return 1 random value.

也会返回一个随机值。

#5

Personally, I would prefer the method item = myArray.random_element.

就个人而言，我更喜欢方法项= myArray.random_element。

UPDATE: If you aren't using rails (active support) you'll need to define the method yourself. See Marc-André Lafortune's answer for a more modern view. You could also define the Array#sample method similar to this, if you are using ruby version < 1.9.1.

更新:如果您没有使用rails(主动支持)，您需要自己定义方法。看看Marc-Andre Lafortune对更现代的观点的回答。如果您使用的是ruby版本< 1.9.1，您也可以定义类似于此的数组#样例方法。

class Array
  def random_element
    self[rand(length)]
  end
end