From: Allen Mitchell <ajm@...>
Date: 2002-10-21T10:07:38+09:00
Subject: Re: Grouping by twos

I ran into the same requirement and I solved it by extending the Array
class.  Have a look...

class Array
	#---------------------------------------------------------------------
	# each_group
	#---------------------------------------------------------------------
	def each_group ( sizeof )
		limitOf = length-1
		0.step( limitOf, sizeof ) { |i| yield( self[i,sizeof] ) }
	end

	#---------------------------------------------------------------------
	# collect_each_group
	#---------------------------------------------------------------------
	def collect_each_group ( sizeof )
		rtn = []
		limitOf = length-1
		0.step( limitOf, sizeof ) { |i| rtn << yield( self[i,sizeof] ) }
		rtn
	end
end

a = [ 1,2,3,4,5,6,7,8,9,10 ]
b = a.collect_each_group(2) { |items| items }
 and b = [[1,2],[3,4],[5,6],[7,8],[9,10]]

Hope it helps...


-----Original Message-----
From: Martin DeMello [mailto:martindemello@yahoo.com]
Sent: October 20, 2002 19:52
To: ruby-talk ML
Subject: Grouping by twos


Another of those trivial little problems that I obsess about finding
the Proper way to do - what's a nice, idiomatic Ruby way to go from
[a,b,c,d.....] to [[a,b],[c,d],[e,f],...]? Note that I want to
preserve the ordering, so to_hash won't work.

One way I thought of was
b = []
while a[0] do
  b << [a.shift, a.shift]
end

which works but doesn't look particularly elegant.

martin