From: 7stud -- <bbxx789_05ss@...>
Date: 2011-04-03T03:32:23+09:00
Subject: Re: Simple array.each do |x| question

Kyle X. wrote in post #990532:
>
> So once I flatten the array it would become - > [0,1,2,3,4,5,6,7,8] from
> [[0,1,2],[3,4,5],[6,7,8]] correct?
>

Yes, and you can always test that.  If you use:

  p some_array

ruby will output the array structure.

> This would then allow me to all in one .to_f, yes?  Would this be
> possible to do without flattening, or is it not possible with arrays in
> an array?
>

You wouldn't want to flatten in that case.  Instead you can use some 
nested map() calls:

data = [[0,1,2],[3,4,5],[6,7,8]]

transformed_data = data.map do |arr|
   arr.map do |int|
     int.to_f
   end
end

p transformed_data

--output:--
[[0.0, 1.0, 2.0], [3.0, 4.0, 5.0], [6.0, 7.0, 8.0]]

map() sends each element of the data array to the block parameter arr. 
Because each element of the data array is a sub-array, I named the block 
parameter 'arr' to indicate that.  Now that you have a reference to the 
sub-array inside the outer block, you can apply another map() to the 
subarray to do the actual transformation.  The inner map() block returns 
a new array that has transformed one of the data sub-arrays to floats. 
And the outer map stuffs each of those returned-transformed-arrays into 
a new array--producing the final result.

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