CODEWITHSUNDEEP
ruby
hancho
hancho

Reputation: 1437

Ruby, is there a built in method to split an array into two sub arrays at a specified index?

Doing a ruby problem and thinking to myself, there must be an easier way.

I want to split an array at a specified index into two sub arrays. The first sub array containing the numbers up to the specified index, and the second sub array containing the numbers after and including the specified index.

Example 

([2, 1, 2, 2, 2],2) => [2,1] [2,2,2]
#here, the specified index is two, so the first array is index 0 and 1, 
the second is index 2, 3, and 4. 

def array_split(arr,i)
  arr1 = []
  arr2 = []
  x = 0

  while x < arr.count 
    x < i ? arr1 << arr[x] : arr2 << arr[x]
    x += 1
 end 

 return arr1, arr2
end

This was no issue with a while loop. I want to know if there is a simpler solution.

Upvotes: 6

Views: 3677

Answers (4)

Daniel Chae
Daniel Chae

Reputation: 1

For cases where one of the subarrays has length 1, you can use the splat operator.

a = [1, 2, 3]
*b, c = a
b
# => [1, 2]
c
# => [3]
b, *c = a
b
# => [1]
c
# => [2, 3]

Upvotes: 0

Jokester
Jokester

Reputation: 5617

There is :)

arr1 = [2, 1, 2, 2, 2].take 2 #=> [2, 1]
arr2 = [2, 1, 2, 2, 2].drop 2 #=> [2, 2, 2]

Upvotes: 6

raquelhortab
raquelhortab

Reputation: 556

Note that there is also values_at which can take single items, items at different positions, and ranges of positions:

a = [0,1,2,3,4,5,6,7,8,9]
a.values_at(1,3)
# => [1, 3]
a.values_at(3..7)
# => [3, 4, 5, 6, 7]

Upvotes: 0

DigitalRoss
DigitalRoss

Reputation: 146053

def split a, i
  [a[0...i], a[i..-1]]
end

p split [2,1,2,2,2], 2

# here is another way

class Array
  def split i
    [self[0...i], self[i..-1]]
  end
end

p [2,1,2,2,2].split 2

Upvotes: 2

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