CODEWITHSUNDEEP
arraysruby
treeseal7
treeseal7

Reputation: 749

iterate through and map a multi-dimensional array

I want to apply a function to each of the values at all levels of the array:

arr = [[1,2,3],[1,2,3],[[1,2],[1,2]],1,2,3]

for example, multiply all the values by 3, and map it in the same format as before so I get:

arr = [[3,6,9],[3,6,9],[[3,6],[3,6]],3,6,9]

What would be the best way to go about this?

Upvotes: 2

Views: 121

Answers (2)

Nic Nilov
Nic Nilov

Reputation: 5156

Use recursion. Create a method that will call itself if the element is array, do your calculation if it is not.

def walk_array(array)
  array.map do |element|
    if element.is_a?(Array)
      walk_array(element)
    else
      element * 3
    end
  end
end

arr = [[1,2,3],[1,2,3],[[1,2],[1,2]],1,2,3] 
# => [[1, 2, 3], [1, 2, 3], [[1, 2], [1, 2]], 1, 2, 3]

walk_array(arr) 
# => [[3, 6, 9], [3, 6, 9], [[3, 6], [3, 6]], 3, 6, 9]

Upvotes: 3

user12341234
user12341234

Reputation: 7193

If you're open to using a gem, I wrote a module that provides exactly this functionality: https://github.com/dgopstein/deep_enumerable

>> require 'deep_enumerable'
>> arr = [[1,2,3],[1,2,3],[[1,2],[1,2]],1,2,3]

>> arr.deep_map_values{|x| x*3}
=> [[3, 6, 9], [3, 6, 9], [[3, 6], [3, 6]], 3, 6, 9]

Upvotes: 0

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