I have an array of numbers. I want to convert it to an array of ranges. Example:
input = [0,10,20,30]
output = [0..10, 10..20, 20..30, 30..Infinity]
Is there some direct way to do it in Ruby?
2 Answers
Yes, possible :
input = [0,10,20,30]
(input + [Float::INFINITY]).each_cons(2).map { |a,b| a..b }
# => [0..10, 10..20, 20..30, 30..Infinity]
3 Comments
sawa
You have an array of ranges, but the OP asks for an array of arrays (which does not make sense, given the example). You are not answering the OP's question, but it is not your fault. It is the OP's fault.
Arup Rakshit
@sawa Humm,, you are right. I assumed he wanted to get array of ranges.
Stefan
You could use the shorthand
.map { |a,b| a..b } instead of Range.newOne way:
Code
output = input.zip(input[1..-1] << 1.0/0).map { |r| Range.new(*r) }
Explanation
input = [0,10,20,30]
a = input[1..-1]
#=> [10, 20, 30]
b = a << 1.0/0
#=> [10, 20, 30, Infinity]
c = input.zip(b)
#=> [[0, 10], [10, 20], [20, 30], [30, Infinity]]
output = c.map { |r| Range.new(*r) }
#=> [0..10, 10..20, 20..30, 30..Infinity]
Possible alternative
If you instead wanted an array of arrays, you would just change the block:
output = input.zip(input[1..-1] << 1.0/0).map { |f,l| [f..l] }
#=> [[0..10], [10..20], [20..30], [30..Infinity]]
[0-10]meant to be[0, 1, ..., 10]? Then what is[30-infinity]?