I have very little knowledge about Ruby and cant find a way to create 2d array. Can anyone provide me some snippets or information to get me started?
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5 Answers
The easiest way to create a 2d array is by the following:
arr1 = Array.new(3) { Array.new(3)}
The code above creates a 2D array with three rows and three columns.
Cheers.
Comments
a = [[1, 2], [3, 4]]
a.each do |sub|
sub.each do |int|
puts int
end
end
# Output:
# 1
# 2
# 3
# 4
or:
a = [[1, 2], [3, 4]]
a.each do |(x, y)|
puts x + y
end
# Output:
# 3
# 7
Comments
irb(main):001:0> a = []
=> []
irb(main):002:0> a1 = [1, 2]
=> [1, 2]
irb(main):003:0> a2 = [3, 4]
=> [3, 4]
irb(main):004:0> a.push a1
=> [[1, 2]]
irb(main):005:0> a.push a2
=> [[1, 2], [3, 4]]
irb(main):006:0> a
=> [[1, 2], [3, 4]]
irb(main):007:0> a[0]
=> [1, 2]
irb(main):008:0> a[0][1]
=> 2
1 Comment
notapatch
Good explanation of creating a 2D array but I does not seem to answer the second part of the question about iterating the 2D array. Currently, the full answer means you should read both this and simonmenke answers - which may be confusing. :)
Ruby doesn't have the concept of 2-dimensional arrays like C does. Arrays in Ruby are dynamic -- meaning you can resize them a will. They can contain any object or value in each "slot" - including another Array!
In the examples given by @JunaidKirkire and @simonmenke, you have an array which has arrays for its values. You can access the values using the syntax similar to C - but you could also have the case where one slot is an Array and another is just a number, or a String, or a Hash...
You may want to work through a Ruby tutorial to get a better idea of how it works. I like RubyMonk but there are other good ones out there as well.
Comments
Creating a 2d array in Ruby
In ruby, every method accepts a block.
two_d_array = Array.new(3) do
Array.new(3) do
0
end
end
The same can be written In oneline (macro style)
two_d_array = Array.new(3) { Array.new(3) { 0 } }
Output
[
[0, 0, 0],
[0, 0, 0],
[0, 0, 0]
]
Iterating a 2d array in Ruby
I can think of three ways.
1: Using range
(0...two_d_array.size).each do |i|
(0...(two_d_array[i].length)).each do |j|
puts two_d_array[i][j]
end
end
2: Using for
for i in (0...two_d_array.size)
for j in (0...two_d_array[i].length)
puts two_d_array[i][j]
end
end
3: Using Each_with_index method
two_d_array.each_with_index do |sub_array, i|
sub_array.each_with_index do |item, j|
puts two_d_array[i][j]
end
end
