CODEWITHSUNDEEP
rubyrandomgenerator
m_vdbeek
m_vdbeek

Reputation: 3774

Negative random numbers

I know how to generate numbers with Rails but I don't know how to generate negative numbers?

prng.rand(1..6) for random of [1, 2, 3, 4, 5, 6]

Random doc says that you would get an ArgumentError.

Upvotes: 6

Views: 3075

Answers (5)

Mörre
Mörre

Reputation: 5723

How about you multiply the positive random number by -1

Upvotes: 5

thomallen
thomallen

Reputation: 2034

I needed to generate a random integer, either 1 or -1 and I used this:

prng = Random.new(1)    
prng.rand > 0.5 ? 1 : -1

Upvotes: 0

Radhika
Radhika

Reputation: 2559

Suppose you want to generate negative numbers between -1 to -5

You can simply do this:

rand(-5..-1)

It will generate random numbers between -5 to -1

Upvotes: 7

Pepe
Pepe

Reputation: 6480

Let's say you want to generate a number between a and b you can always do that using this formula:

randomNum = (b-a)*prng.rand + a

So if you want a number between -8 and +7 for example then a=-8 and b=7 and your code would be

randomNum = (7-(-8))*prng.rand + (-8)

which is equivalent to

randomNum=15*prng.rand - 8

Upvotes: 9

Steven Jackson
Steven Jackson

Reputation: 434

def rand(a, b)
  return Random.rand(b - a + 1) + a 
end
rand(-3, 5)

Upvotes: 3

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