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Revision 1.3 - (hide annotations) (download) (as text)
Mon May 16 18:10:46 2005 UTC (13 years, 3 months ago) by agriffis
Branch: MAIN
Changes since 1.2: +19 -10 lines
File MIME type: text/x-perl
ranking works completely now, even if it needs badly to be refactored

1 agriffis 1.3 # $Id: Votify.pm,v 1.2 2005/05/16 04:03:46 agriffis Exp $
2 agriffis 1.1 #
3     # Copyright 2005 Gentoo Foundation
4     # Distributed under the terms of the GNU General Public License v2
5     #
6     # votify.pm: common classes for votify and countify
7     #
8    
9     package Votify;
10    
11     use POSIX;
12     use List::Util;
13     use strict;
14    
15     our ($datadir) = '/home/agriffis/elections';
16     (our $zero = $0) =~ s,.*/,,;
17    
18     sub import {
19 agriffis 1.2 my ($class, $mode) = @_;
20     $Votify::mode = $mode;
21 agriffis 1.1 }
22    
23     ######################################################################
24     # OfficialList
25     ######################################################################
26    
27     package OfficialList;
28    
29     sub new {
30 agriffis 1.2 my ($class, $election) = @_;
31     my ($self) = {
32     election => $election,
33     officials => [],
34     };
35 agriffis 1.1
36 agriffis 1.2 # no point in waiting to load
37     open(F, "<$Votify::datadir/officials-$election")
38     or die("failed to open officials file");
39     chomp(@{$self->{'officials'}} = <F>);
40     close(F);
41    
42     bless $self, $class;
43     return $self;
44 agriffis 1.1 }
45    
46     sub officials {
47 agriffis 1.2 my ($self) = @_;
48     @{$self->{'officials'}};
49 agriffis 1.1 }
50    
51     ######################################################################
52     # VoterList
53     ######################################################################
54    
55     package VoterList;
56    
57     sub new {
58 agriffis 1.2 my ($class, $election) = @_;
59     my (@voterlist, $r);
60     my ($self) = {
61     election => $election,
62     default_filename => "$Votify::datadir/confs-$election",
63     filename => '',
64     voters => {}, # confnum => voter
65     confs => {}, # voter => confnum
66     };
67    
68     # no point in waiting to load
69     open(F, "<$Votify::datadir/voters-$election")
70     or die("failed to open voters file");
71     chomp(@voterlist = <F>);
72     close(F);
73 agriffis 1.1
74 agriffis 1.2 # assign confirmation numbers randomly
75     for my $v (@voterlist) {
76     do { $r = int rand 0xffff } while exists $self->{'voters'}{$r};
77     $self->{'voters'}{$r} = $v;
78     $self->{'confs'}{$v} = $r;
79     }
80    
81     unless (keys %{$self->{'voters'}} == keys %{$self->{'confs'}}) {
82     die("discrepancy deteced in VoterList");
83     }
84    
85     bless $self, $class;
86     return $self;
87 agriffis 1.1 }
88    
89     sub confs {
90 agriffis 1.2 my ($self) = @_;
91     sort keys %{$self->{'voters'}};
92 agriffis 1.1 }
93    
94     sub voters {
95 agriffis 1.2 my ($self) = @_;
96     sort keys %{$self->{'confs'}};
97 agriffis 1.1 }
98    
99     sub getvoter {
100 agriffis 1.2 my ($self, $conf) = @_;
101     return $self->{'voters'}{$conf};
102 agriffis 1.1 }
103    
104     sub getconf {
105 agriffis 1.2 my ($self, $voter) = @_;
106     return $self->{'confs'}{$voter};
107 agriffis 1.1 }
108    
109     sub write {
110 agriffis 1.2 my ($self, $filename) = @_;
111 agriffis 1.1
112 agriffis 1.2 $filename ||= $self->{'default_filename'};
113     $self->{'filename'} = $filename;
114 agriffis 1.1
115 agriffis 1.2 if (-f $filename) {
116     die "$filename already exists; please remove it first";
117     }
118    
119     open(F, ">$filename") or die("can't write to $filename");
120     for my $c ($self->confs) {
121     printf F "%04x %s\n", $c, $self->getvoter($c);
122     }
123     close F;
124 agriffis 1.1 }
125    
126     ######################################################################
127     # MasterBallot
128     ######################################################################
129    
130     package MasterBallot;
131    
132 agriffis 1.2 use Data::Dumper;
133    
134 agriffis 1.1 sub new {
135 agriffis 1.2 my ($class, $election, $vl) = @_;
136     my ($self) = {
137     election => $election,
138     default_filename => "$Votify::datadir/master-$election",
139     filename => '',
140     voterlist => $vl,
141     ballots => {}, # indexed by conf num
142     candidates => undef, # indexed by long name
143     table => undef, # indexed by row+column
144     };
145 agriffis 1.1
146 agriffis 1.2 bless $self, $class;
147     return $self;
148 agriffis 1.1 }
149    
150     sub collect {
151 agriffis 1.2 my ($self, @voters) = @_;
152     my ($c, $v, $home, @pwentry);
153    
154     for my $v (@voters) {
155     unless (defined ($c = $self->{'voterlist'}->getconf($v))) {
156     die "$v does not correspond to any confirmation number";
157     }
158 agriffis 1.1
159 agriffis 1.2 @pwentry = getpwnam($v);
160     unless (@pwentry) {
161     print STDERR "Warning: unknown user: $v\n";
162     next;
163     }
164    
165     $home = $pwentry[7];
166     unless (-d $home) {
167     print STDERR "Warning: no directory: $home\n";
168     next;
169     }
170    
171     if (-f "$home/.ballot-$self->{election}-submitted") {
172     my ($b) = Ballot->new($self->{'election'});
173     $b->read("$home/.ballot-$self->{election}-submitted");
174     if ($b->verify) {
175     print STDERR "Errors found in ballot: $v\n";
176     next;
177     }
178     $self->{'ballots'}{$c} = $b;
179     }
180     elsif (-f "$home/.ballot-$self->{election}") {
181     print STDERR "Warning: $v did not submit their ballot\n";
182     }
183     }
184 agriffis 1.1 }
185    
186     sub write {
187 agriffis 1.2 my ($self, $filename) = @_;
188    
189     $filename ||= $self->{'default_filename'};
190     $self->{'filename'} = $filename;
191 agriffis 1.1
192 agriffis 1.2 if (-f $filename) {
193     die "$filename already exists; please remove it first";
194     }
195    
196     open(F, ">$filename") or die("can't write to $filename");
197     for my $c (sort keys %{$self->{'ballots'}}) {
198     printf F "--------- confirmation %04x ---------\n", $c;
199     print F $self->{'ballots'}{$c}->to_s
200     }
201     close F;
202     }
203 agriffis 1.1
204 agriffis 1.2 sub read {
205     my ($self, $filename) = @_;
206     my ($election, $entries) = $self->{'election'};
207    
208     $filename ||= $self->{'default_filename'};
209     $self->{'filename'} = $filename;
210    
211     open(F, "<$filename") or die("can't read $filename");
212     { local $/ = undef; $entries = <F>; }
213     for my $e (split /^--------- confirmation /m, $entries) {
214     next unless $e; # skip the first zero-length record
215     unless ($e =~ /^([[:xdigit:]]{4}) ---------\n(.*)$/s) {
216     die "error parsing entry:\n$e";
217     }
218     my ($c, $s, $b) = ($1, $2, Ballot->new($election));
219     $b->from_s($s);
220     $self->{'ballots'}{hex($c)} = $b;
221     }
222     }
223    
224     sub generate_candidates {
225     my ($self) = @_;
226     my ($B, @C, $s);
227    
228     # nb: would need to scan all the ballots to support write-ins
229     $B = Ballot->new($self->{'election'});
230     $B->populate;
231     @C = sort @{$B->choices};
232     for my $c (map $_->[0], @C) {
233     for (my $i=1; $i<=length($c); $i++) {
234     $s = substr $c, 0, $i;
235     last unless grep(/^$s/, @C) > 1;
236     }
237     $self->{'candidates'}{$c} = $s;
238     }
239     }
240    
241     sub tabulate {
242     my ($self) = @_;
243     my (@candidates); # full candidate list
244     my (%table); # resulting table, row.colum where row defeats column
245     $self->{'table'} = \%table;
246    
247     $self->generate_candidates unless $self->{'candidates'};
248     @candidates = keys %{$self->{'candidates'}};
249     for my $c1 (@candidates) {
250     for my $c2 (@candidates) {
251     $table{"$c1+$c2"} = 0;
252     }
253 agriffis 1.3 $table{"$c1+$c1"} = '***';
254 agriffis 1.2 }
255    
256     # generate the table first;
257     # walk through the ballots, tallying the rankings expressed by each ballot
258     for my $b (values %{$self->{'ballots'}}) {
259     my (@choices, %ranks);
260    
261     #print "looking at ballot:\n", $b->to_s, "\n";
262    
263     # first determine the ranking of each candidate. default ranking is
264     # scalar @candidates.
265     @choices = @{$b->choices};
266     @ranks{@candidates} = (scalar @candidates) x @candidates;
267     #print "ranks before determining:\n", Dumper(\%ranks);
268     for (my $i = 0; $i < @choices; $i++) {
269     @ranks{@{$choices[$i]}} = ($i) x @{$choices[$i]};
270     }
271     #print "ranks after determining:\n", Dumper(\%ranks);
272    
273     # second add the results of all the pairwise races into our table
274     for my $c1 (@candidates) {
275     for my $c2 (@candidates) {
276     next if $c1 eq $c2;
277     $table{"$c1+$c2"}++ if $ranks{$c1} < $ranks{$c2};
278     }
279     }
280     #print "table after adding:\n";
281     #$self->display_table;
282     }
283     }
284    
285     sub display_table {
286     my ($self) = @_;
287     my (@longnames, @shortnames);
288     my ($minlen, $maxlen, $formatstr) = (0, 4, '');
289    
290     $self->generate_candidates unless $self->{'candidates'};
291     @longnames = sort keys %{$self->{'candidates'}};
292     @shortnames = sort values %{$self->{'candidates'}};
293     $minlen = length scalar keys %{$self->{'ballots'}};
294     $minlen = 5 if $minlen < 5;
295    
296     # build the format string
297     for my $s (@shortnames) {
298     if (length($s) > $minlen) {
299     $formatstr .= " %" . length($s) . "s";
300     } else {
301     $formatstr .= " %${minlen}s";
302     }
303     }
304     map { $maxlen = length($_) if length($_) > $maxlen } @longnames;
305    
306     # prepend the row header; append newline
307     $formatstr = "%${maxlen}s" . $formatstr . "\n";
308    
309     # column headers
310     printf $formatstr, '', @shortnames;
311    
312     # rows
313     for my $l (@longnames) {
314     printf $formatstr, $l, @{$self->{'table'}}{map "$l+$_", @longnames};
315     }
316     }
317    
318     # utility for cssd
319     sub defeats {
320     my ($self, $o1, $o2) = @_;
321     return 0 if $o1 eq $o2;
322     $self->{'table'}{"$o1+$o2"} > $self->{'table'}{"$o2+$o1"};
323     }
324    
325     # utility for cssd
326     sub is_weaker_defeat {
327     my ($self, $A, $X, $B, $Y) = @_;
328     die unless $self->defeats($A, $X);
329     die unless $self->defeats($B, $Y);
330     return (
331     $self->{'table'}{"$A+$X"} < $self->{'table'}{"$B+$Y"} or
332     (
333     $self->{'table'}{"$A+$X"} == $self->{'table'}{"$B+$Y"} and
334     $self->{'table'}{"$X+$A"} > $self->{'table'}{"$Y+$B"}
335     )
336     );
337     }
338    
339     sub cssd {
340     my ($self) = @_;
341     my (@candidates);
342    
343     @candidates = sort keys %{$self->{'candidates'}};
344    
345     while (1) {
346     my (%transitive_defeats);
347     my (@active, @plist);
348    
349     ######################################################################
350     # 5. From the list of [undropped] pairwise defeats, we generate a
351     # set of transitive defeats.
352     # 1. An option A transitively defeats an option C if A
353     # defeats C or if there is some other option B where A
354     # defeats B AND B transitively defeats C.
355     for my $o1 (@candidates) {
356     for my $o2 (@candidates) {
357     $transitive_defeats{"$o1+$o2"} = 1 if $self->defeats($o1, $o2);
358     }
359     }
360     for my $i (@candidates) {
361     for my $j (@candidates) {
362     for my $k (@candidates) {
363     if (exists $transitive_defeats{"$j+$i"} and
364     exists $transitive_defeats{"$i+$k"})
365     {
366     $transitive_defeats{"$j+$k"} = 1;
367     }
368     }
369     }
370     }
371    
372     ######################################################################
373     # 6. We construct the Schwartz set from the set of transitive
374     # defeats.
375     # 1. An option A is in the Schwartz set if for all options B,
376     # either A transitively defeats B, or B does not
377     # transitively defeat A.
378     print "\n";
379     A: for my $A (@candidates) {
380     for my $B (@candidates) {
381     next if $transitive_defeats{"$A+$B"} or not $transitive_defeats{"$B+$A"};
382 agriffis 1.3 # countify marks entries +++ instead of *** when they've already
383     # been ranked.
384     if ($self->{'table'}{"$A+$A"} eq '***') {
385     print "option $A is eliminated ($A does not beat $B and $B beats $A)\n";
386     }
387 agriffis 1.2 next A;
388     }
389     push @active, $A;
390     }
391     print "the Schwartz set is {", join(", ", @active), "}\n";
392     @candidates = @active;
393    
394     ######################################################################
395     # 7. If there are defeats between options in the Schwartz set, we
396     # drop the weakest such defeats from the list of pairwise
397     # defeats, and return to step 5.
398     # 1. A defeat (A,X) is weaker than a defeat (B,Y) if V(A,X)
399     # is less than V(B,Y). Also, (A,X) is weaker than (B,Y) if
400     # V(A,X) is equal to V(B,Y) and V(X,A) is greater than V
401     # (Y,B).
402     # 2. A weakest defeat is a defeat that has no other defeat
403     # weaker than it. There may be more than one such defeat.
404     for my $o1 (@candidates) {
405     for my $o2 (@candidates) {
406     push @plist, [ $o1, $o2 ] if $self->defeats($o1, $o2);
407     }
408     }
409     last unless @plist;
410     @plist = sort {
411     return -1 if $self->is_weaker_defeat(@$a, @$b);
412     return +1 if $self->is_weaker_defeat(@$b, @$a);
413     return 0;
414     } @plist;
415     for my $dx (@plist) {
416     my ($o1, $o2) = @$dx;
417 agriffis 1.3 print("$o1+$o2 ",
418     $self->{'table'}{"$o1+$o2"}, " $o2+$o1 ",
419 agriffis 1.2 $self->{'table'}{"$o2+$o1"}, "\n");
420     }
421     my ($o1, $o2) = @{$plist[0]};
422     $self->{'table'}{"$o1+$o2"} = 0;
423     $self->{'table'}{"$o2+$o1"} = 0;
424     }
425    
426     ######################################################################
427     # 8. If there are no defeats within the Schwartz set, then the
428     # winner is chosen from the options in the Schwartz set. If
429     # there is only one such option, it is the winner. If there
430     # are multiple options, the elector with the casting vote
431     # chooses which of those options wins.
432     print "\n";
433     if (@candidates > 1) {
434     print "result: tie between options ", join(", ", @candidates), "\n";
435     } else {
436     print "result: option @candidates wins\n";
437     }
438 agriffis 1.3
439     return @candidates;
440 agriffis 1.1 }
441    
442     ######################################################################
443     # Ballot
444     ######################################################################
445    
446     package Ballot;
447    
448     sub new {
449     my ($class, $election) = @_;
450     my ($self) = {
451     election => $election,
452     filename => '',
453     default_filename => $ENV{'HOME'}."/.ballot-$election",
454     choices => [],
455     };
456    
457     # Bless me, I'm a ballot!
458     bless $self, $class;
459     return $self;
460     }
461    
462 agriffis 1.2 sub from_s {
463     my ($self, $s) = @_;
464     my (@choices);
465    
466     for (split "\n", $s) {
467     s/#.*//;
468     next unless /\S/;
469     push @choices, [ split(' ', $_) ];
470     }
471     die("No data in string") unless @choices;
472    
473     $self->{'choices'} = \@choices;
474     }
475    
476     sub read {
477 agriffis 1.1 my ($self, $filename) = @_;
478    
479     $filename ||= $self->{'default_filename'};
480     $self->{'filename'} = $filename;
481    
482     # Load the data file
483     open(F, "<$filename") or die("couldn't open $filename");
484 agriffis 1.2 { local $/ = undef; $self->from_s(<F>); }
485 agriffis 1.1 close(F);
486     }
487    
488     sub populate {
489     my ($self) = @_;
490 agriffis 1.2 $self->read("$Votify::datadir/ballot-$self->{election}");
491 agriffis 1.1 @{$self->{'choices'}} = List::Util::shuffle(@{$self->{'choices'}});
492     }
493    
494     sub choices {
495 agriffis 1.2 my ($self) = @_;
496     $self->{'choices'};
497 agriffis 1.1 }
498    
499     sub write {
500     my ($self, $filename) = @_;
501    
502 agriffis 1.2 if ($Votify::mode ne 'user') {
503     die("we don't write ballots in official mode");
504     }
505 agriffis 1.1
506     $filename ||= $self->{'default_filename'};
507     $self->{'filename'} = $filename;
508    
509     # Don't ever overwrite a ballot
510     die("File already exists; please remove $filename\n") if -e $filename;
511    
512     # Write the user's ballot
513     open(F, ">$filename") or die "Failed writing $filename";
514     print F <<EOT;
515     # This is a ballot for the $self->{election} election.
516     # Please rank your choices in order; first choice at the top and last choice at
517     # the bottom. You can put choices on the same line to indicate no preference
518     # between them. Any choices you omit from this file are implicitly added at the
519     # end.
520     #
521     # When you're finished editing this, the next step is to verify your ballot
522     # with:
523     #
524     # $Votify::zero --verify $self->{election}
525     #
526     # When that passes and you're satisfied, the final step is to submit your vote:
527     #
528     # $Votify::zero --submit $self->{election}
529     #
530    
531     EOT
532     for (@{$self->{'choices'}}) { print F "@$_\n"; }
533     close(F);
534     }
535    
536     sub verify {
537     my ($self) = @_;
538     my (%h, $master, %mh);
539     my (@dups, @missing, @extra);
540     my ($errors_found);
541    
542     # Load %h from the user's ballot
543     for my $line (@{$self->{'choices'}}) {
544     for my $entry (@$line) {
545     $h{$entry}++;
546     }
547     }
548    
549     # Load the master ballot into another hash and compare them.
550     # The master ballots always do one entry per line, making this a little
551     # easier.
552     $master = Ballot->new($self->{'election'});
553     $master->populate;
554     %mh = map(($_->[0] => 1), @{$master->{'choices'}});
555    
556     # Check for extra entries (write-ins should be supported in the future)
557     for (keys %h) {
558     push @extra, $_ unless exists $mh{$_};
559     }
560    
561     # Check for duplicate entries
562     @dups = grep { $h{$_} > 1 } keys %h;
563    
564     # Check for missing entries (not necessarily an error)
565     for (keys %mh) {
566     push @missing, $_ unless exists $h{$_};
567     }
568    
569     # Report errors and warnings
570     if (@extra) {
571     if ($Votify::mode eq 'user') {
572     print <<EOT;
573     Your ballot has some extra entries that are not part of this election. Sorry,
574     but write-ins are not (yet) supported. Please remove these from your ballot:
575    
576     EOT
577     print map "\t$_\n", @extra;
578     print "\n";
579     }
580     $errors_found++;
581     }
582     if (@dups) {
583     if ($Votify::mode eq 'user') {
584     print <<EOT;
585     Your ballot has some duplicate entries. Please resolve these to a single entry
586     to avoid ambiguities:
587    
588     EOT
589     print map "\t$_\n", @dups;
590     print "\n";
591     }
592     $errors_found++;
593     }
594     if (@{$self->{'choices'}} == 0) {
595     if ($Votify::mode eq 'user') {
596     print <<EOT;
597     Your ballot doesn't contain any entries. You can start over by first removing
598     the existing ballot, then using --new to generate a new ballot. See --help for
599     more information.
600    
601     EOT
602     }
603     $errors_found++;
604     }
605     elsif (@missing and $Votify::mode eq 'user') {
606     print <<EOT;
607     Your ballot is missing some entries. This is not an error, but note that these
608     will be implied as a final line, with no preference between them, like this:
609    
610     EOT
611     print "\t", join(" ", @missing), "\n";
612     print "\n";
613     }
614     if ($Votify::mode eq 'user' and !$errors_found and
615     @{$self->{'choices'}} == 1 and
616     scalar(keys %h) == scalar(keys %mh))
617     {
618     print <<EOT;
619     Your ballot contains all the candidates on a single line! This means you have
620     no preference between the candidates. This is not an error, but note that this
621     is a meaningless ballot that will have no effect on the election.
622    
623     EOT
624     }
625    
626     # Stop if there were errors
627     if ($Votify::mode eq 'user' and $errors_found) {
628     print("There were errors found in your ballot.\n");
629     die("Please correct them and try again.\n\n");
630     }
631     return $errors_found;
632     }
633    
634 agriffis 1.2 sub to_s {
635     my ($self) = @_;
636     join '', map "@$_\n", @{$self->{'choices'}};
637     }
638    
639 agriffis 1.1 1;
640    
641     __END__
642    
643 agriffis 1.3 $Log: Votify.pm,v $
644     Revision 1.2 2005/05/16 04:03:46 agriffis
645     add first pass at countify --rank
646    
647 agriffis 1.1
648     __END__
649    
650 agriffis 1.3 $Log: Votify.pm,v $
651     Revision 1.2 2005/05/16 04:03:46 agriffis
652     add first pass at countify --rank
653    
654 agriffis 1.1 Revision 1.3 2005/05/09 23:12:02 agriffis
655     Add support for registered voters
656    
657     Revision 1.2 2005/05/05 23:03:46 agriffis
658     Fix indentation (and some output as well)
659    
660     Revision 1.1 2005/05/05 22:05:34 agriffis
661     first pass at Gentoo Foundation voting program
662    
663 agriffis 1.2 # vim:sw=4 et

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