Ruby multidimensional array

Solution 1:

Strictly speaking it is not possible to create multi dimensional arrays in Ruby. But it is possible to put an array in another array, which is almost the same as a multi dimensional array.

This is how you could create a 2D array in Ruby:

a = [[1,2,3], [4,5,6], [7,8,9]]

require 'narray'
b = NArray[ [1,2,3], [4,5,6], [7,8,9] ]

Use a[i][j] to access the elements of the array. Basically a[i] returns the 'sub array' stored on position i of a and thus a[i][j] returns element number j from the array that is stored on position i.

Solution 2:

you can pass a block to Array.new

Array.new(n) {Array.new(n,default_value)}

the value that returns the block will be the value of each index of the first array,

so..

Array.new(2) {Array.new(2,5)} #=> [[5,5],[5,5]]

and you can access this array using array[x][y]

also for second Array instantiation, you can pass a block as default value too. so

Array.new(2) { Array.new(3) { |index| index ** 2} } #=> [[0, 1, 4], [0, 1, 4]]