How to randomly pick either 4 or 5?

Question

With ruby on rails, ruby, how can I randomly select either 4 or 5?

possible duplicate of [How to get a random number in Ruby?](http://stackoverflow.com/questions/198460/how-to-get-a-random-number-in-ruby) — Felix Kling, Feb 14 '12 at 17:38
I understand closing this as a duplicate, but why the downvotes? It's clearly worded, on topic, and something that would not be obvious to a new Ruby programmer. — jdl, Feb 14 '12 at 18:04

score 5 · Answer 1 · answered Feb 14 '12 at 17:33

5

Just use Ruby's rand function:

4+rand(2)
=> 4
4+rand(2)
=> 5
4+rand(2)
=> 5

answered Feb 14 '12 at 17:33

coudy

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score 5 · Answer 2 · answered Feb 14 '12 at 17:34

5

I like a nice simple one liner.

(4..5).to_a.sample

answered Feb 14 '12 at 17:34

MrDanA

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4

Why overcomplicating? `[4, 5].sample` – Sergio Tulentsev Feb 14 '12 at 17:35
+1 for using `Array#sample`. However, no need to create a Range. Simply use `%w( 4 5 ).sample`. – Simone Carletti Feb 14 '12 at 17:37
Ha that's true, Sergio. I just usually go straight to ranges because usually it's between larger numbers (like `(1..100)`) but yeah in this case that be easier. – MrDanA Feb 14 '12 at 17:38
1

@SimoneCarletti: that would be array of strings. Not cool. – Sergio Tulentsev Feb 14 '12 at 17:39
@SergioTulentsev You're right, but it depends on what you need to do. ;) – Simone Carletti Feb 14 '12 at 17:59

score 3 · Accepted Answer · edited Feb 15 '12 at 03:05

3

four_or_five = rand(2) == 0 ? 4 : 5

Since rand(num) chooses a value between 0 and num, non-inclusive, there's a 50% chance of 0 being chosen. Thus, four_or_five will be 4 or 5 with equal probability.

edited Feb 15 '12 at 03:05

Eric Hu

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answered Feb 14 '12 at 17:33

Sergio Tulentsev

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score 2 · Answer 4 · edited Feb 14 '12 at 20:11

2

In Ruby 1.9.3 I think you can just do:

rand(4..5)

edited Feb 14 '12 at 20:11

steenslag

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answered Feb 14 '12 at 17:38

AlistairH

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How to randomly pick either 4 or 5?

4 Answers4