How to select array elements in a given range in Ruby?

Question

I have an array with let\'s say, 500 elements. I know I can select the first 100 by doing .first(100), my question is how do I select elements from 100 to 200?

Answer 1

new_array = old_array.first(200) - old_array.first(100)

Answer 2

dvcolgan’s answer is right, but it sounds like you might be trying to break your array into groups of 100. If that’s the case, there’s a convenient built-in method for that:

nums = (1..500).to_a

nums.each_slice(100) do |slice|
  puts slice.size
end

# => 100, 100, 100, 100, 100

Answer 3

You can do it like this:

array[100..200] # returns the elements in range 100..200
# or
array[100,100] # returns 100 elements from position 100

More Information

Answer 4

You can use ranges in the array subscript:

arr[100..200]

Answer 5

sample_array = (1..500).to_a
elements_100_to_200 = sample_array[100..200]

You can pass a range as index to an array and get a subarray with the queried elements from that subrange.