From: Robert Klemme <shortcutter@...>
Date: 2009-12-14T01:35:13+09:00
Subject: Re: Code block for element comparison in an array?

On 13.12.2009 16:13, Derek Cannon wrote:
> Jose Hales-Garcia wrote:
>> #method 2
>> a.each_with_index do |e1,i|
>>    a[(i+1)..a.length].each do |e2|
>>      # Compare e1 and e2
>>    end
>> end
> 
> a[(i+1)..a.length].each
> ^ That blew my mind Jose!

It's a bit inefficient as it will create n intermediate Arrays.  Also, 
the range should be (i+1) ... a.length (i.e. excluding a.length). 
Here's a variant which does not create all the intermediate sub arrays:

a.each_with_index do |e, i|
   for j in i+1 ... a.length
     puts "compare #{e} to #{a[j]}"
   end
end

Here are more solutions with less math (no "i+1"):

a.each_with_index do |e, i|
   for j in 0 ... i
     puts "compare #{e} to #{a[j]}"
   end
end

a.each_with_index do |e, i|
   i.times do |j|
     puts "compare #{e} to #{a[j]}"
   end
end

Note, these does compare in a different order.

Of course there are a lot more variants... :-)

Cheers

	robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/