Get Random Element(s) from a List

Question

I'm basically looking for an Elixir equivalent of Ruby's Array#sample. Something that would let me do this:

list = [1,2,3,4,5,6,7]  sample(list) #=> 4  sample(list, 3) #=> [6, 2, 5] 

I didn't find anything in the Elixir List Docs either.

Answer 1

Updated Answer

As José Valim said in his answer, in Elixir 1.1 and above, you can now use these methods to get random element(s) from a list:

• Enum.random/1 - For getting single random element
• Enum.take_random/2 - For getting multiple random elements

Example:

Enum.random(list)                         #=> 4  Enum.take_random(list, 3)                 #=> [3, 9, 1] Enum.take_random(list, 1)                 #=> [7] 

Remember to call :random.seed(:erlang.now) first!

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Original Answer

I'm still unable to find a 'proper' and 'magical' way to do this, but this is the best I could come up:

For getting a single random element:

list |> Enum.shuffle |> hd #=> 4 

Note: This gives an exception if the list is empty

For getting multiple random elements:

list |> Enum.shuffle |> Enum.take(3) #=> [7, 1, 5] 

Answer 2

There is no such function in Elixir 1.0, so you need to implement it yourself as mentioned by the other solutions. However, Enum.random/1 is coming with Elixir v1.1: https://hexdocs.pm/elixir/Enum.html#random/1