[EM] Re: Condorcet package-wvx

[Daniel Bishop]

Dave Ketchum wrote:

> On Fri, 25 Feb 2005 00:01:11 -0800 Russ Paielli wrote:
>
> ...
>
>> On the theoretical side, what exactly would an equal-ranking 
>> capability accomplish? Does it give the voter some significant 
>> strategic mechanism, or is it simply way for the voter to express 
>> indecision? If it's the latter, then it is completely unnecessary. If 
>> the voter truly rates the candidates as precisely equal down to the 
>> tenth decimal place, then it really shouldn't matter to him which he 
>> ranks above the other. If the decision is really that difficult, he 
>> can flip a coin. Why make the system more complicated than it needs 
>> to be?
>
>
> Conceded it complicates the counting, though I do not see that as major.

It doesn't complicate the counting.  Especially if you use the code from 
my website.

def pairwise_matrix(ballots):
   """Return a matrix M such that M[i][j] = votes for candidate #i over #j.

   ballots = a list of ballots, where each ballot is a list B with each
             B[i] = the rank (1=best) of candidate #i"""
   if not ballots:
      return []
   n = len(ballots[0]) # number of candidates
   matrix = [[0] * n for i in xrange(n)]
   for ballot in ballots:
      if len(ballot) != n:
         raise ValueError("ballots have unequal lengths")
      for i in xrange(n):
         for j in xrange(n):
            if ballot[i] < ballot[j]: # i preferred over j
               matrix[i][j] += 1

Note that there's not even an explicit test for equal rankings.

(The GUI is simply a row of radio buttons for each candidate, each 
corresponding to a rank,)