From: Lars Haugseth <ruby-talk@...>
Date: 2012-06-26T18:48:13+09:00
Subject: Re: Array#sample is Set#sample and not Array#sample !

On 06/25/2012 11:03 PM, Ryan Davis wrote:
>
> On Jun 25, 2012, at 09:55 , Bartosz Dziewo��ski wrote:
>
>> 2012/6/25 Robert Klemme <shortcutter@googlemail.com>:
>>> I am sorry, I don't get it.  Can you explain what your expectation is?
>>
>> I think he wants to keep the ordering or original array in the result
>> of #sample.
>>
>> This might actually make sense.
>
> So you would expect `(1..3).to_a.sample(3)` to always output [1, 2, 3] ?
>
> That doesn't make sense to me.

I agree, sample isn't intended to work the way the OP suggests.

There are other ways to achieve the desired effect:

   class Array
     def ordered_sample(n)
       values_at [*0...size].sample(n).sort
     end
   end

   a = [:a, :b, :c, :d, :e, :f, :g, :h]

   a.ordered_sample(4)
   => [:b, :c, :d, :e]
   a.ordered_sample(4)
   => [:c, :d, :e, :h]
   a.ordered_sample(4)
   => [:a, :b, :c, :g]

-- 
Lars Haugseth