use utf8;
use autodie;
use bigrat;
+use Carp;
+use Data::Dumper;
+use List::Util qw(sum0);
use List::MoreUtils qw(nsort_by);
# vote is
our $places = shift @ARGV;
die unless $places eq ($places + 0);
+open DEBUG, ">.stv.log" or die $!;
+
while (<>) {
next if m/^\w+$/;
m/^(\w+) ([A-Z]+)$/ or die "$_ ?";
- my $prefs = $1;
+ my $prefs = $2;
my $vote = {
Voter => $1,
Weight => 1.0,
sub pr ($) {
my ($f) = @_;
- return sprintf "%10.6f=%-10s", $f, $f;
+ confess unless defined $f;
+ return sprintf "%10.6f = %-10s", $f, $f;
}
sub votelog ($$) {
# $sorted{$firstpref}{Votes} = [ $vote, ... ]
# $sorted{$firstpref}{Cand} = $firstpref
# $sorted{$firstpref}{Total} = $totalweight
-our @sorted; # values same as %sorted
our @surpluses; # values same as %sorted
our @exhausted; # votes
$continuing{$_}=1 foreach @{ $vote->{Prefs} };
}
+sub equalpiles ($@) {
+ my ($how, @sorted) = @_;
+ return () unless @sorted;
+ my $s = $sorted[0];
+ my $eqtotal = $s->{Total};
+ my $count = 0;
+ while ($count < @sorted && $sorted[$count]{Total} == $eqtotal) {
+ printf "%7s %10s %s\n", $how, $sorted[$count]{Cand},
+ pr $sorted[$count]{Total};
+ $count++;
+ }
+ return @sorted[ 0 .. $count-1 ];
+}
+
+sub historically_prefer ($@) {
+ my ($signum, @choices) = @_;
+
+ return $choices[0] if @choices < 2;
+
+ my $compare = sub {
+ foreach my $sr (@stagerecord) {
+ my $d = $sr->{ $a->{Cand} } <=> $sr->{ $b->{Cand} };
+ return $d * $signum if $d;
+ }
+ return 0;
+ };
+
+ @choices = sort $compare, @choices;
+ $a = $choices[0];
+ my $numequal = 0;
+ for (;;) {
+ last unless $numequal >= @choices;
+ $b = $choices[$numequal];
+ last if $compare->();
+ }
+
+ die 'random choice unimplemented' if $numequal > 1;
+ return $choices[0];
+}
+
for (;;) {
$stage++;
+ printf "----- stage %d -----\n", $stage;
+
+ print DEBUG "#################### $stage ####################\n",
+ Data::Dumper->Dump(
+[ \@stagerecord, \@elected, \@unsorted, \%sorted, \@surpluses, \%continuing ],
+[qw( _@stagerecord _@elected _@unsorted _%sorted _@surpluses _%continuing )]
+ );
+
while (my $vote = shift @unsorted) {
my ($firstpref) = grep { $continuing{$_} } @{ $vote->{Prefs} };
if (!defined $firstpref) {
}
$sorted{$_}{Cand} = $_ foreach keys %sorted;
foreach my $firstpref (sort keys %sorted) {
+ $sorted{$firstpref}{Total} = 0; # recount
foreach my $vote (@{ $sorted{$firstpref}{Votes} }) {
votelog $vote, "counted $vote->{Weight} for $firstpref";
$sorted{$firstpref}{Total} += $vote->{Weight};
}
}
- my @sorted = nsort_by { -$_->{Total} } values %sorted;
+ my @sorted;
+ my $sort_update = sub {
+ @sorted = nsort_by { -$_->{Total} } values %sorted;
+ };
+ $sort_update->();
+
+ print DEBUG "SORTED\n", Dumper(\@sorted);
push @stagerecord, { map { ($_->{Cand}, $_->{Total}) } @sorted };
$countvalid->(\@sorted, '1stpref');
$countvalid->(\@surpluses, 'surplus');
- printf "%7s %10s %s\n", 'TOTAL', '', pr $totalvalid;
+ printf "%7s %10s %s\n", 'TOTAL', '-----', pr $totalvalid;
unless ($totalvalid > 0) {
printf "No more votes!\n";
}
my $quota = $totalvalid / ($placesremain + 1);
- printf "%7s %10s %s\n", '', 'quota', pr $quota;
+ printf "%7s %10s %s\n", 'quota', '', pr $quota;
my $need_to_transfer_surplus = 1;
# (ERS rules 5.4.9)
for (;;) {
my $s = $sorted[0];
- my $topvoters = $s->{Weight};
+ my $topvoters = $s->{Total};
my $surplus = $topvoters - $quota;
last unless $surplus > 0;
- printf "%7s %10s\n", 'ELECTED', $s->{Cand};
+ printf "%7s %10s ***************\n", 'ELECTED', $s->{Cand};
push @elected, $s->{Cand};
my $derate = $topvoters / $surplus;
- printf "%7s %10s\n", 'derate', $s->{Cand}, pr $derate;
+ printf "%7s %10s %s\n", 'derate', $s->{Cand}, pr $derate;
foreach my $vote (@{ $s->{Votes} }) {
- votelog $vote, "elected $s->{Cand}, derated $weightmult";
+ votelog $vote, "elected $s->{Cand}, derated $derate";
$vote->{Weight} /= $derate;
}
- shift @sorted;
push @surpluses, $s;
- delete %sorted->{ $s->{Cand} };
+ delete $sorted{ $s->{Cand} };
delete $continuing{ $s->{Cand} };
+ $sort_update->();
$need_to_transfer_surplus = 0;
# before actually transferring a surplus, we will consider
# eliminating, and then reconsider with a lower quota
}
+ my $deferredsurplus = sum0 map { $_->{Total} } @surpluses;
+ printf "%18s %s\n", 'deferred surplus', pr $deferredsurplus;
+
# Look for people to eliminate
# We eliminate before trying to transfer surpluses
# ERS 5.2.5
+ for (;;) {
+ last unless @sorted;
+
+ printf "%18s\n", 'elimination round';
+
+ my @elim = equalpiles 'elim?', reverse @sorted;
+ my $elimvotetotal = sum0 map { $_->{Total} } @elim;
+
+ if (@surpluses) {
+ if (@sorted == @elim) {
+ printf "%18s\n", 'no-elim, un-defer, (all-equal)';
+ last;
+ }
+ my $nextup = $sorted[ $#sorted - @elim ];
+ printf "%7s %10s %s\n", 'nextup', $nextup->{Cand},
+ pr $nextup->{Total};
+ my $aheadby = $nextup->{Total} - $elimvotetotal;
+ unless ($deferredsurplus <= $aheadby) {
+ # rule 5.2.2 (b)
+ printf "%18s %s\n", 'no-elim, un-defer', pr $aheadby;
+ last;
+ }
+ }
+
+ if ((scalar keys %continuing) - (scalar @elim) < $placesremain) {
+ # eliminate only one then, and try again
+ printf "elim-tie!\n";
+ @elim = historically_prefer -1, @elim;
+ }
+
+ foreach my $s (@elim) {
+ my $c = $s->{Cand};
+ printf "%7s %10s %s\n", 'ELIM', $c, '----------';
+ my $votes = $s->{Votes};
+ votelog $_, "failed to stop $c elimination" foreach @$votes;
+ delete $continuing{$c};
+ delete $sorted{$c};
+ push @unsorted, @$votes;
+ }
+
+ $sort_update->();
+ $need_to_transfer_surplus = 0;
+ }
-
- # transfer the surplus
- filterout $topfirst, "candidate was elected";
- } else {
- my $elim = $sorted{ $#sorted };
- printf "%10s eliminated\n", $elim;
- filterout $elim, "candidate was eliminated";
+ next unless $need_to_transfer_surplus;
+
+ @surpluses = nsort_by { $_->{Total} } @surpluses;
+ my @surplusxfer = equalpiles 'xfer?', @surpluses;
+ die unless @surplusxfer;
+
+ if (@surplusxfer > 1) {
+ @surplusxfer = historically_prefer +1, @surplusxfer;
}
+
+ my $s = $surplusxfer[0];
+ my $c = $s->{Cand};
+ printf "%7s %10s\n", 'xfer', $c;
+ my $votes = $s->{Votes};
+ votelog $_, "surplus transferred" foreach @$votes;
+ @surpluses = grep { $_->{Cand} ne $c } @surpluses;
+ push @unsorted, @$votes;
}
+
+print "done.\n";
~ian / appendix-a6.git / blobdiff