# Weight => 1.0 }
# We edit Prefs as we go
+# $cands{CAND}{Cand}
# $cands{CAND}{Desc}
# $cands{CAND}{Votes}
# $cands{CAND}{Total}
-# $cands{CAND}{Continuing}
+# $cands{CAND}{NonCont} # undef, or Elected or Eliminated
our $seats=0;
+our @allvotes;
+our @non_transferable;
+our %cands;
our $stage=0;
our $quota;
our %tie;
$cands{$cand}{Desc} = $desc;
} elsif (m/^(\w*) :\s*(.*)\s*\|(.*)/) {
my ($voter,$prefs,$opts) = ($1,$2,$3);
- $v = { Voter => $voter };
+ my $v = { Voter => $voter };
push @{ $v->{Prefs} }, [ $_ =~ m/\w+/g ]
foreach split /\s+/, $prefs;
foreach $_ (split / /, $opts) {
- if (m/^_?[Ww]eight=(\d+)/(\d+)$/) {
+ if (m/^_?[Ww]eight=(\d+)\/(\d+)$/) {
$v->{Weight} = $1 / $2;
} elsif (m/^_?[Ww]eight=([0-9.]+)$/) {
$v->{Weight} = new Math::BigRat $1;
}
}
-$_->{Continuing} = 1 foreach values %cands;
+$cands{$_}{Cand} = $_ foreach keys %cands;
+
+sub votelog ($$) {
+ my ($vote,$m) = @_;
+ push @{ $vote->{Log} }, "stage $stage: $m";
+}
sub sortballots (@) {
# Takes each argument, which should be a ballot, sorts
my $firstprefs = shift @{ $v->{Prefs} };
my $w = $v->{Weight};
if (!$firstprefs || !@$firstprefs) {
- vlog $v, "no more preferences, non transferable";
+ votelog $v, "no more preferences, non transferable";
push @non_transferable, $v;
next;
}
if (@$firstprefs > 1) {
- vlog $v, "splitting due to several equal first preferences";
+ votelog $v, "splitting due to several equal first preferences";
foreach my $fpref (@$firstprefs) {
my $v2 = {
%$v,
Weight => $w / @$firstprefs,
Prefs => [ [ $fpref ], @{ $v->{Prefs} } ],
};
- vlog $v, "split for $fpref";
+ votelog $v, "split for $fpref";
}
next;
}
- my $fp = $firstprefs[0];
+ my $fp = $firstprefs->[0];
my $c = $cands{$fp};
- if (!$c->{Continuing}) {
- vlog $v, "dropping pref $fp, not a continuing candidate";
+ my $noncont = $c->{NonCont};
+ if ($noncont) {
+ votelog $v, "dropping pref $fp, $noncont";
sortvallots $v;
next;
}
- vlog $v, "sorted into pile for candidate $fp weight $w";
+ votelog $v, "sorted into pile for candidate $fp weight $w";
push @{ $c->{Votes} }, $v;
}
}
}
sub countballots () {
- foreach my $c (values %cand) {
+ foreach my $cand (sort keys %cands) {
+ my $c = $cands{$cand};
+ next if $c->{NonCont};
$c->{Total} = 0;
$c->{Total} += $_->{Weight} foreach @{ $c->{Voters} };
- }
- foreach my $cand (sort keys %cand) {
- $c = $cands{$cand};
- next unless $c->{Continuing};
prf "cand %s: %s votes\n", $stage, $cand, $c->{Total};
$c->{History}[$stage-1] = $c->{Total};
}
}
sub total_history_cmp () {
- my $ha = $cands{a}{History};
- my $hb = $cands{a}{History};
+ my $ha = $a->{History};
+ my $hb = $b->{History};
foreach my $s (reverse 1 .. $stage) {
my $d = $ha->[$s] <=> $hb->[$s];
next unless $d;
- print DEBUG "history cmp $a $b => $d (#$s $ha->[$s] $hb->[$s])\n";
- return $e;
+ print DEBUG "history cmp $a->{Cand} $b->{Cand}".
+ " => $d (#$s $ha->[$s] $hb->[$s])\n";
+ return $d;
}
return 0;
}
+sub continuing () {
+ grep { !$_->{NonCont} } values %cands;
+}
+
+sub select_best_worst ($$$$) {
+ my ($wantcand, $wanttiebreak, $signum, $what) = @_;
+ # $wantcand->($c) = boolish
+ # $wanttiebreak->($total) = boolish
+ # Firstly candidates not meeting $wantcand are ignored
+ # Then we pick the best (worst) candiate by Total (or vote history).
+ # (SLGEO 49(2) and 51(2).
+ # If this does not help then totals are equal and we call wanttiebreak.
+ # If it returns 0 we return alphabetically first CAND. Otherwise
+ # we tie break.
+
+ my @maybe = grep { $wantcand->($_) } continuing();
+ @maybe = sort total_history_cmp @maybe;
+ @maybe = reverse @maybe if $signum > 0;
+
+ return undef unless @maybe;
+
+ my $nequal = 1;
+
+ for (;;) {
+ my $nextc = $maybe[$nequal];
+
+ # Only interested in those who compare equal according to the
+ # history (SLGEO 49(2)); NB our history includes the current
+ # round.
+
+ last if $signum*($a = $maybe[0], $b = $nextc, total_history_cmp) > 0;
+ $nextc++;
+ }
+
+ if ($nequal > 1 && !$wanttiebreak->($maybe[0]{Total})) {
+ # ... if equal for election we can do them one by one, since
+ # order does not matter (SLGEO 49 talks about `two or more
+ # ... exceeds').
+ $nequal = 1;
+ }
+
+ my $selectcand;
+ if ($nequal > 1) {
+ my @all = map { $_->{Cand} } @maybe[0 .. $nequal-1];
+ my $tiekey = $signum > 0 ? 'Win' : 'Lose';
+ my $win = $tie{"@all"}{$tiekey};
+ die "need tie break, want $tiekey from @all" unless defined $win;
+ prf "$what %s due to tie break amongst %s\n",
+ $selectcand, "@all";
+ } else {
+ $selectcand = $maybe[0];
+ prf "$what %s\n";
+ }
+
+ return $cands{$selectcand};
+}
+
+sub elect_core ($) {
+ my ($c) = @_;
+ prf "*** ELECT %s \`%s' ***\n", $c->{Cand}, $c->{Desc};
+ $c->{NonCont} = 'Elected';
+}
+
sortballots @allvotes;
for (;;) {
$stage++;
- countballots();
-
- my @maybe_elect = reverse sort total_history_cmp keys %cands;
- my $nelect=0;
- for (;;) {
- my $nextcand = $maybe_elect[$nelect];
- my $nextc = $cands{$nextcand};
-
- # We certainly only consider those who meet quota
- last unless $nextc->{Total} >= $quota;
- last unless $nextc->{Total} > $quota && $nextel;
- # ... if equal we can do them one by one, since order
- # does not matter (SLGEO 49 talks about `two or more ... exceeds')
-
- last if $nelect &&
- (total_history_cmp $maybe_elect[0], $nextcand) > 0;
- # ... only interested in those who compare equal
- # according ot the history (SLGEO 49(2)); NB our history
- # includes the current round.
-
- $nelect++;
- }
- if ($nelect) {
- my $elect;
- if ($nelect > 1) {
- my @all = @maybe_elect[0 .. $nelect-1];
- my $elect = $tie{"@all"}{Win};
- die "need tie break, want winner from @all" unless defined $win;
- prf "electing %s due to tie break amongst %s\n",
- $elect, "@all";
- } else {
- $elect = $maybe_elect[0];
- prf "electing %s\n";
+ my $seats_remain = $seats
+ - grep { $_->{NonCont} eq 'Elected' } values %cands;
+ if (continuing() <= $seats_remain) {
+ foreach my $c (continuing()) {
+ prf "electing %s to fill remaining place(s)\n", $c->{Cand};
+ elect_core $c;
}
+ last;
+ }
- prf "*** ELECT %s ***\n", $elect;
- $c->{Continuing} = 0;
- votelog $_, "helped elect $elect" foreach @{ $c->{Votes} };
+ countballots();
+
+ my $c = select_best_worst
+ sub { $_->{Total} >= $quota },
+ sub { $_ > $quota },
+ +1, 'electing';
+
+ if ($c) {
+ elect_core $c;
+ votelog $_, "helped elect $c->{Cand}" foreach @{ $c->{Votes} };
# SLGEO 48
- my $c = $cands{$elect};
my $surplus = $c->{Total} - $quota;
if ($surplus <= 0) {
foreach my $v (@{ $c->{Votes} }) {
my $A = $surplus * $v->{Weight};
my $F = 100000;
- my $xfervalue = floor(($A * $F) / $B) / $f;
+ my $xfervalue = floor(($A * $F) / $B) / $F;
# SLGEO 48(3): we do arithmetic to 5 d3ecimal places,
# but always rounding down
votelog $v, "transferring with value $xfervalue (A=$A B=$B)";
next;
}
-
+ # No-one to elect, must eliminate
+ $c = select_best_worst
+ sub { 1; },
+ sub { 1; },
+ -1, 'eliminating';
+
+ if ($c) {
+ prf "=== eliminating %s (%s) ===\n", $c->{Cand}, $c->{Desc};
+ $c->{NonCont} = 'Eliminated';
+ next;
+ }
+
+ die;
+}
+
+print "done.\n";
~ian / appendix-a6.git / blobdiff