From: Josh Cheek <josh.cheek@...>
Date: 2011-11-28T00:16:25+09:00
Subject: Re: Creating 2-D array from 1-D array

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On Sun, Nov 27, 2011 at 7:06 AM, J. Marshal <windbreiz@gmail.com> wrote:

> Hello, I am relatively new to Ruby.  I have an existing array:
>   a = [1 , 2 , 3 , 4 , 5 , 6]
> and I want to create this 2-D array:
>   b = [[1 , 2][2 , 4][5 , 6]]
> I am using the following code, which works, but seems somewhat clumsy:
>    b = Array.new
>    i = 0
>    k = 0
>    for item in a
>      if i == 0
>        a1 = item
>        i = 1
>      elsif i == 1
>        a2 = item
>        i = 0
>        b[k] = [a1, a2]
>        puts "b..#{k},  #{b[k]}"
>        k = k + 1
>      end
>    end
> I would appreciate any advice to make this code look more elegant or
> ruby-like.  In particular, I suspect there is a way to avoid the
> indices.
> Thanks for the help.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

# There are some very helpful methods in Enumerable
# (http://rubydoc.info/stdlib/core/1.9.3/Enumerable).
# In this case, check out each_slice.

ary = [1 , 2 , 3 , 4 , 5 , 6]
sliced = ary.each_slice 2

sliced # => #<Enumerator: [1, 2, 3, 4, 5, 6]:each_slice(2)>



# You can think of it like the array you showed,
# for instance you can iterate over its elements
# or map them to new values or whatever.

sliced.each do |element|
  element # => [1, 2], [3, 4], [5, 6]
end

sliced.map(&:reverse) # => [[2, 1], [4, 3], [6, 5]]



# But if you really need an array, you can get it with to_a

sliced.to_a # => [[1, 2], [3, 4], [5, 6]]

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