X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=stv;h=fbd7b41050b18f535931223c8b7e0d8534c9f095;hb=0328306e06758d9fb43cec21611d044eda1acf09;hp=47984e80dc4bdb286f8d2f271d4e3701e7089b72;hpb=83ac3d9b8d6e365ca3f7083db8f37034456da0be;p=appendix-a6.git

diff --git a/stv b/stv
index 47984e8..fbd7b41 100755
--- a/stv
+++ b/stv
@@ -6,9 +6,10 @@
 use strict;
 use utf8;
 use autodie;
-#use bigrat;
+use bigrat;
+use Carp;
 use Data::Dumper;
-use List::Util qw(sum);
+use List::Util qw(sum0);
 use List::MoreUtils qw(nsort_by);
 
 # vote is
@@ -27,7 +28,7 @@ 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,
@@ -38,7 +39,8 @@ while (<>) {
 
 sub pr ($) {
     my ($f) = @_;
-    return sprintf "%10.6f=%-10s", $f, $f;
+    confess unless defined $f;
+    return sprintf "%10.6f = %-10s", $f, $f;
 }
 
 sub votelog ($$) {
@@ -46,16 +48,6 @@ sub votelog ($$) {
     push @{ $vote->{Log} }, "stage $stage: $m";
 }
 
-sub filterout ($$) {
-    my ($cand, $why) = @_;
-    foreach my $vote (@allvotes) {
-	my $oldprefs = $vote->{Prefs};
-	my @prefs = grep { $_ ne $cand } $oldprefs;
-	next if @prefs == @$oldprefs;
-	votelog $vote, "crossed out candidate $cand: $why";
-    }
-}
-
 our @elected; # $elected[] = $candidate
 
 our @unsorted = @allvotes;
@@ -72,6 +64,17 @@ our %continuing; # $continuing{$candidate}=1
 
 our @stagerecord; # $stagerecord[]{$candidate} = $total
 
+sub voteliveprefs ($) {
+    my ($vote) = @_;
+    grep { $continuing{$_} } @{ $vote->{Prefs} };
+}
+
+sub votelogfull ($$) {
+    my ($vote,$m) = @_;
+    votelog $vote, $m;
+    votelog $vote, ("continuing prefs: ". join ' ', voteliveprefs $vote);
+}
+
 foreach my $vote (@allvotes) {
     $continuing{$_}=1 foreach @{ $vote->{Prefs} };
 }
@@ -83,7 +86,8 @@ sub equalpiles ($@) {
     my $eqtotal = $s->{Total};
     my $count = 0;
     while ($count < @sorted && $sorted[$count]{Total} == $eqtotal) {
-	printf "%7s %10s\n", $how, $sorted[$count]{Cand};
+	printf "%7s %10s %s\n", $how, $sorted[$count]{Cand},
+	    pr $sorted[$count]{Total};
 	$count++;
     }
     return @sorted[ 0 .. $count-1 ];
@@ -115,17 +119,33 @@ sub historically_prefer ($@) {
     return $choices[0];
 }
 
+foreach my $c (keys %continuing) {
+    $sorted{$c} = {
+        Cand => $c,
+        Votes => [],
+    };
+}
+
 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 )]
 	   );
 
+    my $placesremain = $places - @elected;
+
+    unless ($placesremain > 0) {
+	printf "Complete.\n";
+	last;
+    }
+
     while (my $vote = shift @unsorted) {
-	my ($firstpref) = grep { $continuing{$_} } @{ $vote->{Prefs} };
+	my ($firstpref) = voteliveprefs $vote;
 	if (!defined $firstpref) {
 	    votelog $vote, "ballot exhausted";
 	    push @exhausted, $vote;
@@ -133,18 +153,21 @@ for (;;) {
 	    push @{ $sorted{$firstpref}{Votes} }, $vote;
 	}
     }
-    $sorted{$_}{Cand} = $_ foreach keys %sorted;
     foreach my $firstpref (sort keys %sorted) {
 	foreach my $vote (@{ $sorted{$firstpref}{Votes} }) {
 	    votelog $vote, "counted $vote->{Weight} for $firstpref";
-	    $sorted{$firstpref}{Total} += $vote->{Weight};
 	}
     }
     my @sorted;
-    my $sort_update = sub {
+    my $things_update = sub {
+	foreach my $s (@surpluses, values %sorted) {
+	    $s->{Total} = sum0 map { $_->{Weight} } @{ $s->{Votes } };
+	}
 	@sorted = nsort_by { -$_->{Total} } values %sorted;
     };
-    $sort_update->();
+    $things_update->();
+
+    print DEBUG "SORTED\n", Dumper(\@sorted);
 
     push @stagerecord, { map { ($_->{Cand}, $_->{Total}) } @sorted };
 
@@ -159,22 +182,15 @@ for (;;) {
     $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";
 	last;
     }
 
-    my $placesremain = $places - @elected;
-
-    unless ($placesremain > 0) {
-	printf "Complete.\n";
-	last;
-    }
-
     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;
 
@@ -183,15 +199,15 @@ for (;;) {
     # (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 $derate";
@@ -201,31 +217,56 @@ for (;;) {
 	delete $sorted{ $s->{Cand} };
 	delete $continuing{ $s->{Cand} };
 
-	$sort_update->();
+	$things_update->();
+	printf "%7s %10s %s\n", 'surplus', $s->{Cand}, pr $s->{Total};
+
 	$need_to_transfer_surplus = 0;
 	# before actually transferring a surplus, we will consider
 	# eliminating, and then reconsider with a lower quota
     }
 
-    my $deferredsurplus = sum map { $_->{Total} } @surpluses;
-    printf "%7s %10s %s\n", 'def.srp', 'total', pr $deferredsurplus;
+    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
+    my $elimvotebefore = 0;
     for (;;) {
 	last unless @sorted;
 
-	my @elim = equalpiles 'elim?', reverse @sorted;
-	my $elimvote = sum map { $_->{Total} } @elim;
-	my $elimvotetotal = $elimvote * scalar @elim;
+	if ($elimvotebefore) {
+	    printf "%18s %s\n", 'elimination, sofar', pr $elimvotebefore;
+	} elsif (@surpluses) {
+	    printf "%18s\n", 'elimination, maybe';
+	} else {
+	    printf "%18s\n", 'elimination, starts';
+	}
 
-	if (@surpluses and $elimvotetotal > $deferredsurplus) {
-	    printf "no-elim, un-defer\n";
-	    last;
+	my @elim = equalpiles 'elim?', reverse @sorted;
+	my $elimvotenow = sum0 map { $_->{Total} } @elim;
+
+	if (@surpluses || $elimvotebefore) {
+	    # rule 5.2.2
+	    if (@sorted == @elim) {
+		printf "%18s\n", 'no-elim (all-equal)';
+		last;
+	    }
+	    my $nextup = $sorted[ $#sorted - @elim ];
+	    printf "%7s %10s %s\n", 'nextup', $nextup->{Cand},
+		pr $nextup->{Total};
+	    my $aheadby = $nextup->{Total} - ($elimvotenow + $elimvotebefore);
+	    unless ($deferredsurplus <= $aheadby) {
+		# rule 5.2.2 (b)
+		printf "%18s %s\n", 'no-elim (nextup)', pr $aheadby;
+		last;
+	    }
 	}
 
-	if ((scalar keys %continuing) - (scalar @elim) < $placesremain) {
+	my $elim_tie =
+	    @elim > 1 &&
+	    (scalar keys %continuing) - (scalar @elim) < $placesremain;
+	if ($elim_tie) {
 	    # eliminate only one then, and try again
 	    printf "elim-tie!\n";
 	    @elim = historically_prefer -1, @elim;
@@ -233,21 +274,23 @@ for (;;) {
 
 	foreach my $s (@elim) {
 	    my $c = $s->{Cand};
-	    printf "%7s %10s\n", 'ELIM', $c;
+	    printf "%7s %10s %s\n", 'ELIM', $c, '----------';
 	    my $votes = $s->{Votes};
-	    votelog $_, "failed to stop $c elimination" foreach @$votes;
+	    votelogfull $_, "failed to stop $c elimination" foreach @$votes;
+	    $elimvotebefore += $s->{Total};
 	    delete $continuing{$c};
 	    delete $sorted{$c};
 	    push @unsorted, @$votes;
 	}
 	
-	$sort_update->();
+	$things_update->();
 	$need_to_transfer_surplus = 0;
+	last if $elim_tie; # no more, then!
     }
     
     next unless $need_to_transfer_surplus;
 
-    @surpluses = nsort_by { $_->{Total} }, @surpluses;
+    @surpluses = nsort_by { $_->{Total} } @surpluses;
     my @surplusxfer = equalpiles 'xfer?', @surpluses;
     die unless @surplusxfer;
 
@@ -259,7 +302,7 @@ for (;;) {
     my $c = $s->{Cand};
     printf "%7s %10s\n", 'xfer', $c;
     my $votes = $s->{Votes};
-    votelog $_, "surplus transferred" foreach @$votes;
+    votelogfull $_, "surplus transferred" foreach @$votes;
     @surpluses = grep { $_->{Cand} ne $c } @surpluses;
     push @unsorted, @$votes;
 }