CODEWITHSUNDEEP
ruby
daremkd
daremkd

Reputation: 8424

Getting the last x numbers from an infinite sequence in Ruby

This works in Ruby:

a = 4..Float::INFINITY
p a.take(4) #=> [4,5,6,7]

But I was wondering if it's possible to do something similar where the range would be from negative infinity up to a certain number, say 4, and have a method that will take the last, say 6 elements from that sequence, which would be [-1,0,1,2,3,4].

Upvotes: 1

Views: 73

Answers (2)

Simone Carletti
Simone Carletti

Reputation: 176382

Getting the last N numbers from a range -infinity..4 is the same of selecting a range of 4..(4-N).

4.downto(4-5).to_a
# => [4, 3, 2, 1, 0, -1]

You can package it as a custom method

def lastn(from, n)
  from.downto(from-n).to_a
end

Upvotes: 1

Raj
Raj

Reputation: 22926

How about the last method?

a.last(6)

Upvotes: 1

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