# Unofficial Ruby Quiz -- Ranking Choices **URL:** \ **Category:** Ruby\ **Created:** [May 4, 2007, 2:06am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309 "2007-05-04T02:06:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 2:06am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/1 "2007-05-04T02:06:23Z")
Apparently some people around here can’t stand Ruby Q. withdrawal. For those people, here’s a quiz question I just came up with. I have a list of some items, and I would like to manually rank which ones are most important to me. But it’s not easy to rank them when I’m looking at them all at once, so I’d like to consider them in pairs and choose from each pair which one is most important to me. Then I’d like to use my answers to those questions to create a ranked list. Anyone think they can come up with a good program to quiz me about these items pairwise, and output a ranking? Extra credit: come up with a solution that lets me take the quiz multiple times, and outputs a single ranked list reflecting all of my sessions taking the quiz. I have my solution to the basic question, but I want to see what other people come up with. –Ken ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 2:42am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/2 "2007-05-04T02:42:24Z")
On 5/3/07, Ken B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Apparently some people around here can’t stand Ruby Q. withdrawal. For > those people, here’s a quiz question I just came up with. > > I have a list of some items, and I would like to manually rank which ones > are most important to me. But it’s not easy to rank them when I’m looking > at them all at once, so I’d like to consider them in pairs and choose > from each pair which one is most important to me. Then I’d like to use my > answers to those questions to create a ranked list. Anyone think they can > come up with a good program to quiz me about these items pairwise, and > output a ranking? Thanks much for filling in. I’m very interested, and I hope I have the time to take a shot at this one. Could you elaborate on the rules a bit? Do all possible pairs have to be evaluated, or should it deduce values based on previous answers? banana is more important than apple orange is more important than banana no need to compare apples to oranges (pardon the pun). > Ken B… PhD candidate. Linguistic Cognition Laboratory. > Department of Computer Science. Illinois Institute of Technology. > [http://www.iit.edu/~kbloom1/](http://www.iit.edu/~kbloom1/) PS: typo on your home page: ‘contected’, looks bad for a linguistics major 😉 ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 5:14am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/3 "2007-05-04T05:14:34Z")
On 5/3/07, Ken B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Ken B… PhD candidate. Linguistic Cognition Laboratory. > Department of Computer Science. Illinois Institute of Technology. > [http://www.iit.edu/~kbloom1/](http://www.iit.edu/~kbloom1/) I wrote a webapp that did something like that using a perverted Condorcet method described here: [http://xkcd.com/date/algorithms.html](http://xkcd.com/date/algorithms.html). I don’t have the code anymore, but that’s a concise way fo doing it. ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 5:20am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/4 "2007-05-04T05:20:34Z")
— Bill G. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > orange is more important than banana > no need to compare apples to oranges (pardon the > pun). I think it would be more fun to leave possibilities like this open: banana is more important than apple orange is more important than banana and apple is more important than orange In the absence of more data, we can’t rank them, but add a few more “things”, and you might be able to (orange is more important than cereal, but apple is not). Hmmm, have to think about this. ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 6:10am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/5 "2007-05-04T06:10:36Z")
On Fri, 04 May 2007 09:41:51 +0900, Bill G. wrote: > > pairwise, and output a ranking? > > Thanks much for filling in. I’m very interested, and I hope I have the > time to take a shot at this one. > > Could you elaborate on the rules a bit? Do all possible pairs have to > be evaluated, or should it deduce values based on previous answers? > > banana is more important than apple > orange is more important than banana > no need to compare apples to oranges (pardon the pun). I guess I’d want to know if I ran into a cycle, but I know that’s a lot more questions. Something else that I would find interesting is having a way to determine the top 10 asking the minimum number of questions. So implement whatever answer you prefer. –Ken P.S. I think the Ruby Q. needs a fourth rule: don’t ask too many questions about what the rules of a particular quiz are. Your variation on the problem may have interesting techniques that nobody else’s has. ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 6:46am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/6 "2007-05-04T06:46:38Z")
On 5/3/07, Ken B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I have a list of some items, and I would like to manually rank which ones > are most important to me. But it’s not easy to rank them when I’m looking > at them all at once, so I’d like to consider them in pairs and choose > from each pair which one is most important to me. Then I’d like to use my > answers to those questions to create a ranked list. Anyone think they can > come up with a good program to quiz me about these items pairwise, and > output a ranking? When does the “no spoiler” period end? ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 6:51am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/7 "2007-05-04T06:51:39Z")
On May 4, 2007, at 9:41 AM, Bill G. wrote: > PS: typo on your home page: ‘contected’, looks bad for a > linguistics major 😉 > > – > Bill G. (aka aGorilla) > The best answer to most questions is “it depends”. > On the contrary, linquistics doesn’t require perfect spelling. ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 4, 2007, 6:20am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/8 "2007-05-04T06:20:37Z")
Ken B. wrote: > I have a list of some items, and I would like to manually rank which ones > are most important to me. But it’s not easy to rank them when I’m looking > at them all at once, so I’d like to consider them in pairs and choose > from each pair which one is most important to me. Topological sort. “man tsort” on most \*nix systems, or [http://en.wikipedia.org/wiki/Topological\_sorting#Algorithms](http://en.wikipedia.org/wiki/Topological_sorting#Algorithms). The rest is just I/O. ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 6, 2007, 3:59am UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/9 "2007-05-06T03:59:52Z")
On 5/3/07, Ken B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > I have a list of some items, and I would like to manually rank which ones > are most important to me. But it’s not easy to rank them when I’m looking > at them all at once, so I’d like to consider them in pairs and choose > from each pair which one is most important to me. Then I’d like to use my > answers to those questions to create a ranked list. Anyone think they can > come up with a good program to quiz me about these items pairwise, and > output a ranking? The way I see it, ranking is nothing more than sorting and choosing between pairs is just the comparison of the sort. So, here is a one-liner given the item list in a file and the questions on stdin: ruby -e ‘puts(ARGF.read.split.sort { |a,b| print “1: #{a}\n2: #{b}\n”; STDIN.gets.to\_i\*2-3}.inspect)’ Eric ---
**Author:** ![sevensoft](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/f9ae1b/32.png) [@sevensoft](https://www.ruby-forum.com/u/sevensoft)\ **Post date:** [May 6, 2007, 5:10pm UTC](https://www.ruby-forum.com/t/unofficial-ruby-quiz-ranking-choices/103309/10 "2007-05-06T17:10:47Z")
On Thu, 03 May 2007 18:49:09 -0500, Ken B. wrote: > Extra credit: come up with a solution that lets me take the quiz > multiple times, and outputs a single ranked list reflecting all of my > sessions taking the quiz. > > I have my solution to the basic question, but I want to see what other > people come up with. Here’s a solution that uses tsort, the topological sort module from Ruby’s standard library. It asks Theta(n^2) questions, but allows me to specify that two items on the list are really redundant (and have that reflected in the output), and to detect cycles in my preferences that I may need to break somehow. #!/usr/bin/env ruby require ‘rubygems’ require ‘enumerator’ require ‘facets/core/enumerable/each\_unique\_pair’ require ‘tsort’ class Hash include TSort alias tsort\_each\_node each\_key def tsort\_each\_child(node, &block) fetch(node).each(&block) end end LIST=[“Option 1”,“Option 2”,“Option 3”,“Option 4”] RESULTS=Hash.new{|h,k| h[k]=[]} LIST.each{|x| RESULTS[x]} LIST.enum\_for(:each\_unique\_pair). map{|x| x.sort\_by{rand}}. sort\_by{rand}.each do |opt1,opt2| printf "1:%s 2:%s ",opt1,opt2 case readline.chomp when “1”: RESULTS[opt2] \<\< opt1 when “2”: RESULTS[opt1] \<\< opt2 when “=”: RESULTS[opt1] \<\< opt2 RESULTS[opt2] \<\< opt1 else puts “No preference” end end puts #ORDERED LIST RESULTS.strongly\_connected\_components. each{|list| p list}