X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=appendix-a6.git;a=blobdiff_plain;f=compute;h=38ad31b6f0ef85dd4d6aefd135dc3e40d1d74da5;hp=9e5e8ba0d78437704e5a656c10530889aaef80e6;hb=16858a6757d2b921469a29d4974dbd1f7c221e1d;hpb=edc4d0c340cdacbed8a4ae9eb2346bead325045c

diff --git a/compute b/compute
index 9e5e8ba..38ad31b 100755
--- a/compute
+++ b/compute
@@ -4,15 +4,57 @@
 # to Debian Constitution A.6.
 #
 # usage: .../compute [<input files>...]
+#  (uses stdin if none supplied)
 #
-# 
+# input files can be in any order and should contain lines like:
+#
+#   <votername> :: <PREF>, (<PREF>=<PREF>), <PREF>, ....
+#   V: <tallyprefs> <votername>
+#   <ABBREV> = <description...>
+#   <ABBREV> = <description...> [<rat>:<io>]
+#   <ABBREV> = <description...> [default]
+#   nodefault
+#   quorum = <quorum>
+#
+# where
+#
+#   <votername> is any non-whitespace characters
+#
+#   <ABBREV> and <PREF> are abbreviations for choices on the ballot.
+#      They must be ASCII alphanumeric.  Numeric preferences are
+#      not recommended as they are confusing (particularly when
+#      tally sheets are in use).
+#
+#      It is best to avoid FD, SQ and NOTA except for the default
+#      option; if no default option is specified, it will default
+#      to one of these unless a "nodefault" line is found.
+#
+#      In the "::" form, the commas are optional.  Either ( ) or = may
+#      be used to indicate a set of equal preferences.
+#
+#   <tallyprefs> is a tally sheet preference order: that is,
+#      a single uppercase base36 digit for each ballot choice,
+#      (in the order they were specified by "=" lines), giving
+#      the voter's preference rank for that option.  The numbers
+#      need not be distinct or contiguous.  "-" may be used for
+#      unranked preferences.
+#
+#   <rat>:<io> is the majority ratio for the option
+#
+#   <quorum> is the quorum
+#
+# and also allowed are
+#
+#   #-comments                            } all
+#   blank lines                           } ignored
+#   lines starting with whitespace        }
 
 use strict;
 use utf8;
 use autodie;
 
-use Data::Printer;
 use Graph::Directed;
+use Graph::Writer::GraphViz;
 
 binmode STDIN, 'encoding(UTF-8)';
 binmode STDOUT, 'encoding(UTF-8)';
@@ -25,6 +67,19 @@ our @invotes_cc;
 our $defcho;
 our $quorum = 0;
 
+our $gfile;
+
+while (@ARGV && $ARGV[0] =~ /^-/) {
+    local $_ = shift @ARGV;
+    if (m/^--?$/) {
+	last;
+    } elsif (s/^-g//) {
+	$gfile = $_;
+    } else {
+	die "bad usage\n";
+    }
+}
+
 sub addchoice {
     my $choname = shift @_;
     my $cho = $choices{$choname} = {
@@ -66,7 +121,7 @@ our @vab;
 
 # Go through the voters and construct V(A,B)
 
-print "\nParsing \`simple' style ballots\n"
+print "\nParsing \`simple' style ballots\n# devotee-tally-begin\n"
         if @invotes_cc;
 # actually, we pre-parse them into @invotes_v
 # since we want to show them as a tally sheet anyway
@@ -112,6 +167,9 @@ foreach my $iv (@invotes_cc) {
     push @invotes_v, [ $vstr, $voter ];
 }
 
+print "# devotee-tally-end\n"
+        if @invotes_cc;
+
 print "\nDetermining default option\n";
 
 if ($defcho && $defcho->{Index} > -1) {
@@ -124,7 +182,7 @@ if ($defcho && $defcho->{Index} > -1) {
 	last if $defcho;
     }
     if ($defcho) {
-	print "guessed default option was: $choices[$defcho->{Index}]\n";
+	print "guessed default option: $choices[$defcho->{Index}]\n";
     } else {
 	print "could not guess default option, assuming there is none\n";
     }
@@ -236,9 +294,9 @@ sub chremain () {
     return grep { !$ch[$_]{Dropped} } (0..$#ch);
 }
 
-foreach my $ia (chremain()) {
+foreach my $ia (0..$#ch) {
     $defeats->add_vertex($choices[$ia]);
-    foreach my $ib (chremain()) {
+    foreach my $ib (0..$#ch) {
 	my $vab = scalar @{ $vab[$ia][$ib] };
 	my $vba = scalar @{ $vab[$ib][$ia] };
 	next unless $vab > $vba;
@@ -246,6 +304,13 @@ foreach my $ia (chremain()) {
 	print "defeat: $choices[$ia] beats $choices[$ib]",
 	    " ($vab > $vba = +$diff)\n";
 	$defeats->add_edge($choices[$ia],$choices[$ib]);
+	my $label = "$diff($vab:$vba)";
+	if (@invotes_v < 10) {
+	    $label .= "\n". join ' ', @{ $vab[$ia][$ib] };
+	    $label .= "\n/". join ' ', @{ $vab[$ib][$ia] };
+	}
+	$defeats->set_edge_attribute($choices[$ia],$choices[$ib],
+				     label => $label);
     }
 }
 
@@ -266,17 +331,29 @@ sub weaker ($$) {
     return 0;
 }
 
+our $showg = $defeats->deep_copy();
+
+foreach my $ix (0..$#ch) {
+    my $cho = $ch[$ix];
+    next unless $cho->{Dropped};
+    $defeats->delete_vertex($choices[$ix]);
+}
+
 our $schwartz;
 
-for (;;) {
+for (my $dropiter = 1; ; $dropiter++) {
     # loop from A6(5)
 
     print "defeats graph: $defeats\n";
 
-    print "\nTransitive closure A.6(5)\n";
+    print "\nTransitive closure A.6(5) (iteration $dropiter)\n";
 
     my $tdefeats = $defeats->transitive_closure();
 
+    # this makes the debugging output prettier
+    foreach my $ch (@choices) {
+	$tdefeats->delete_edge($ch,$ch);
+    }
     print "closure graph: $tdefeats\n";
 
     print "\nSchwartz set A.6(6)\n";
@@ -325,6 +402,11 @@ for (;;) {
 	my ($ca,$cb) = @$weakest;
 	print "a weakest defeat is $ca > $cb\n";
 	$defeats->delete_edge($ca,$cb);
+	my $label = $showg->get_edge_attribute($ca,$cb,'label');
+	$label .= "\ndropped - weakest in iter.$dropiter";
+	$showg->set_edge_attribute($ca,$cb,'label',$label);
+	$showg->set_edge_attribute($ca,$cb,'style','dotted');
+	$showg->set_edge_attribute($ca,$cb,'graphviz',{constraint=>0});
     }
 
     print "\nDefeats within the Schwartz set, go round again\n";
@@ -333,15 +415,35 @@ for (;;) {
 print "no defeats within the Schwartz set\n";
 print "final schwartz set:\n\n";
 
+my $winxlabel;
 if ($schwartz->vertices() == 1) {
     print "WINNER IS:\n";
+    $winxlabel = "winner";
 } else {
     print "WINNER IS ONE OF (CASTING VOTE DECIDES):\n";
+    $winxlabel = "potential winner";
 }
 
 printf "    %-5s %s\n", $_, $choices{$_}{Desc}
     foreach ($schwartz->vertices());
 
+if (defined $gfile) {
+    foreach my $cho (values %choices) {
+	my $chn = $choices[$cho->{Index}];
+	my $label = "\\$chn\n$cho->{Desc}";
+	if ($cho->{Dropped}) {
+	    $label .= "\nDropped: $cho->{Dropped}";
+	}
+	if ($schwartz->has_vertex($chn)) {
+	    $label .= "\n$winxlabel";
+	}
+	$showg->set_vertex_attribute($chn, 'label', $label);
+    }
+
+    my $gwriter = new Graph::Writer::GraphViz -format => 'ps';
+    $gwriter->write_graph($showg, $gfile);
+}
+
 print ".\n";
 
 #p %choices;