Ruby on Rails

On May 28, 2010, at 9:47 AM, Pale Horse wrote:

> I want to split a single array into 3 columns of equal (or as near
> to as
> possible) length. What would you advise I do?

Well, that depends on whether you want the elements to flow row-wise
or column-wise.

irb> require 'enumerator'
=> true
irb> array = %w[ a b c d e f g h i j k l m n ]
=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
"n"]

## Row-wise is easy

irb> array.each_slice(3) do |a,b,c|
puts [a,b,c]*' '
end
a b c
d e f
g h i
j k l
m n
=> nil

## Column-wise is a bit more work

irb> row_count = (array.length + (3-1))/3
=> 5
irb> columns = []
=> []
irb> array.each_slice(row_count) do |col|
columns << col
columns[-1] << nil while columns[-1].length < row_count
end
=> nil
irb> columns.transpose.each do |a,b,c|
puts [a,b,c]*' '
end
a f k
b g l
c h m
d i n
e j
=> [["a", "f", "k"], ["b", "g", "l"], ["c", "h", "m"], ["d", "i",
"n"], ["e", "j", nil]]

Enjoy!

-Rob

Rob Biedenharn
http://agileconsultingllc.com
Rob@AgileConsultingLLC.com
http://gaslightsoftware.com
rab@GaslightSoftware.com

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