How can I transfer ruby ​​arrays of different sizes?

Question

I have an array:

arr=[[1,2,3],[4,5],[6]], 

I have the following code:

 arr.transpose 

but it does not work, how to solve it?

I get

  [[1,2,3],[4,5],[6]].transpose IndexError: element size differs (2 should be 3) from (irb):13:in `transpose' from (irb):13 from /home/durrant 

my decision:

 arr.reduce(&:zip).map(&:flatten) 

exit:

 [[1, 4, 6], [2, 5, nil], [3, nil, nil]] 

Answer 1

A similar response was sent (but deleted) an hour earlier:

 arr = [[1, 2, 3], [4, 5], [6]] arr[0].zip(*arr[1..-1]) #=> [[1, 4, 6], [2, 5, nil], [3, nil, nil]] 

The above is equivalent to:

 [1, 2, 3].zip([4, 5], [6]) 

This approach assumes that your first subband is always the longest. Otherwise, the result will be truncated:

 arr = [[1, 2], [3, 4, 5], [6]] arr[0].zip(*arr[1..-1]) #=> [[1, 3, 6], [2, 4, nil]] missing: [nil, 5, nil] 

Answer 2

Using zip , as in Stefan's answer, is the easiest, but if you insist on using transpose , then:

 l = arr.map(&:length).max arr.map{|e| e.values_at(0...l)}.transpose # => [[1, 4, 6], [2, 5, nil], [3, nil, nil]] 

Or without using:

 Array.new(arr.map(&:length).max){|i| arr.map{|e| e[i]}} # => [[1, 4, 6], [2, 5, nil], [3, nil, nil]] 

Answer 3

If the length of the subarrays does not match, an IndexError is raised.

 irb(main):002:0> arr=[[1,2,3],[4,5],[6]] => [[1, 2, 3], [4, 5], [6]] irb(main):003:0> arr.transpose IndexError: element size differs (2 should be 3) from (irb):3:in `transpose' from (irb):3 from /Users/liuxingqi/.rvm/rubies/ruby-2.1.2/bin/irb:11:in `<main>' 

it should be:

 irb(main):004:0> arr=[[1,2,3],[4,5,6]] => [[1, 2, 3], [4, 5, 6]] irb(main):005:0> arr.transpose => [[1, 4], [2, 5], [3, 6]] 

or

 irb(main):006:0> arr=[[1,2],[3,4],[5,6]] => [[1, 2], [3, 4], [5, 6]] irb(main):007:0> arr.transpose => [[1, 3, 5], [2, 4, 6]]