X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=blobdiff_plain;f=compute;h=bd9ed7c6ab9e0b01d9a89f4cdcff95eed7ec6c07;hb=5aadf4171505c30873eb9c1cc0deeaa752f095be;hp=222c40f721734c22a72f91aec21474466bb81f0a;hpb=6f39f4a7a7c4404c3e16694ec9ad044f881ab233;p=appendix-a6.git
diff --git a/compute b/compute
index 222c40f..bd9ed7c 100755
--- a/compute
+++ b/compute
@@ -1,10 +1,60 @@
#!/usr/bin/perl -w
+#
+# parses some input about ballots and computes the result according
+# to Debian Constitution A.6.
+#
+# usage: .../compute [...]
+# (uses stdin if none supplied)
+#
+# input files can be in any order and should contain lines like:
+#
+# :: , (=), , ....
+# V:
+# =
+# = [:]
+# = [default]
+# nodefault
+# quorum =
+#
+# where
+#
+# is any non-whitespace characters
+#
+# and 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.
+#
+# 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.
+#
+# : is the majority ratio for the option
+#
+# 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)';
@@ -17,9 +67,24 @@ 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} = { @_, Index => (scalar @choices) };
+ my $cho = $choices{$choname} = {
+ @_, Index => (scalar @choices)
+ };
push @choices, $choname;
return $cho;
}
@@ -29,7 +94,7 @@ while (<>) {
next if m/^\s*\#/;
next unless m/\S/;
next if m/^\s/;
- if (m/^([A-Z]+)\s*\=\s*(\S.*)$/) {
+ if (m/^([A-Z0-9]+)\s*\=\s*(\S.*)$/) {
my ($choname, $desc) = ($1,$2);
my $cho = addchoice($choname, Desc => $desc);
if ($desc =~ m/\[(\d+):(\d+)\]/) {
@@ -43,30 +108,29 @@ while (<>) {
push @invotes_cc, [ $1, "$'" ];
} elsif (m/^quorum = ([0-9.]+)$/) {
$quorum = $1+0.0;
+ } elsif (m/^nodefault$/) {
+ $defcho = { Index => -1 }
} else {
die "invalid input";
}
}
-$defcho ||= $choices{FD};
-if (!$defcho) {
- $defcho = addchoice('FD', Desc => "Further Discussion");
-}
-my $defi = $defcho->{Index};
-die "FD has smaj?!" if $defcho->{Smaj};
-
our @vab;
# $vab[$ia][$ib] = V(A,B)
# Actually, it's a list of voters who prefer A to B (A.6(3)(1))
# Go through the voters and construct V(A,B)
-print "\nPreference matrix\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
foreach my $iv (@invotes_cc) {
$_ = uc $iv->[1];
foreach my $chn (m/\b\w+\b/g) {
- $choices{$chn} or addchoice($chn, Desc => "($chn from voter ballot)");
+ next if $choices{$chn};
+ addchoice($chn, Desc => "($chn from voter ballot)");
}
}
@@ -88,7 +152,7 @@ foreach my $iv (@invotes_cc) {
foreach (split /\s+/) {
foreach (split /=/) {
my $cho = $choices{$_};
- $cho or die "unknown option $_ ($voter)";
+ $cho or die "unknown choice $_ ($voter)";
my $ix = $cho->{Index};
$ranks[$ix] = $rank;
}
@@ -103,6 +167,33 @@ 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) {
+ print "default option was specified: $choices[$defcho->{Index}]\n";
+} elsif ($defcho) {
+ print "no default option\n";
+} else {
+ foreach my $try (qw(FD SQ NOTA)) {
+ $defcho = $choices{$try};
+ last if $defcho;
+ }
+ if ($defcho) {
+ print "guessed default option: $choices[$defcho->{Index}]\n";
+ } else {
+ print "could not guess default option, assuming there is none\n";
+ }
+}
+
+my $defi = $defcho->{Index};
+die "FD has smaj?!" if $defcho->{Smaj};
+
+print "\nParsing devotee tally sheet ballots\n"
+ if @invotes_v > @invotes_cc;
+
foreach my $iv (@invotes_v) {
my ($votestr,$voter) = @$iv;
eval {
@@ -112,7 +203,7 @@ foreach my $iv (@invotes_v) {
my $vchr = $vs[$ix];
if ($vchr eq '-') {
$vs[$ix] = 1000;
- } elsif ($vchr =~ m/[0-9a-z]/) {
+ } elsif ($vchr =~ m/[0-9A-Z]/) {
$vs[$ix] = ord($vchr);
} else {
die "bad vote char";
@@ -130,6 +221,8 @@ foreach my $iv (@invotes_v) {
die "voter $voter $@" if $@;
}
+print "\nPreference matrix\n";
+
our @ch = map { $choices{$_} } @choices;
# Print the counts V(A,B)
@@ -168,27 +261,29 @@ sub drop ($$) {
$ch[$i]{Dropped} = $why;
}
-print "\nQuorum A.6(2) (quorum is $quorum)\n";
+if (defined $defi) {
+ print "\nQuorum A.6(2) (quorum is $quorum)\n";
-foreach my $i (0..$#choices) {
- next if $ch[$i]{Dropped};
- next if $i == $defi;
- my $v = $vab[$i][$defi];
- next if $v >= $quorum;
- drop $i, "quorum ($v < $quorum)";
-}
+ foreach my $i (0..$#choices) {
+ next if $ch[$i]{Dropped};
+ next if $i == $defi;
+ my $v = $vab[$i][$defi];
+ next if $v >= $quorum;
+ drop $i, "quorum ($v < $quorum)";
+ }
-print "\nMajority ratio A.6(3)\n";
-
-foreach my $i (0..$#choices) {
- next if $ch[$i]{Dropped};
- next if $i == $defi;
- my $majr = $ch[$i]{Smaj};
- $majr ||= [1,1]; # A.6(3)(3)
- my $vad = scalar @{ $vab[$i][$defi] };
- my $vda = scalar @{ $vab[$defi][$i] };
- next if $vad * $majr->[1] > $vda * $majr->[0];
- drop $i, "majority ratio ($vad * $majr->[1] <= $vda * $majr->[0])";
+ print "\nMajority ratio A.6(3)\n";
+
+ foreach my $i (0..$#choices) {
+ next if $ch[$i]{Dropped};
+ next if $i == $defi;
+ my $majr = $ch[$i]{Smaj};
+ $majr ||= [1,1]; # A.6(3)(3)
+ my $vad = scalar @{ $vab[$i][$defi] };
+ my $vda = scalar @{ $vab[$defi][$i] };
+ next if $vad * $majr->[1] > $vda * $majr->[0];
+ drop $i, "majority ratio ($vad:$vda <= $majr->[1]:$majr->[0])";
+ }
}
print "\nDefeats A.6(4)\n";
@@ -199,9 +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;
@@ -209,6 +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);
}
}
@@ -229,17 +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: $tdefeats\n";
print "\nSchwartz set A.6(6)\n";
@@ -288,6 +402,11 @@ for (;;) {
my ($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";
@@ -296,15 +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;