X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?p=appendix-a6.git;a=blobdiff_plain;f=compute-scottish-stv;h=12645fd4d64da0ce5b13aea6f435afc48c8935d9;hp=d92db96382bddeac989202ad6e937ca8f52f6ce6;hb=af19a4306f157650f182d15cf4e02325f372b2d7;hpb=5fc4bc0993f2f2dc97c43217b3c0bfc51cdf9415

diff --git a/compute-scottish-stv b/compute-scottish-stv
index d92db96..12645fd 100755
--- a/compute-scottish-stv
+++ b/compute-scottish-stv
@@ -31,6 +31,10 @@ our %cands;
 our $stage=0;
 our $quota;
 our %tie;
+our @elected;
+
+our $DIGS = 5;
+our $F = (new Math::BigRat 10)->bpow($DIGS);
 
 open DEBUG, ">.compute.log" or die $!;
 DEBUG->autoflush(1);
@@ -54,6 +58,8 @@ $SIG{__DIE__} = sub {
     die $_[0];
 };
 
+sub total_history_cmp ();
+
 sub unkopt ($$) {
     my ($what,$opt) = @_;
     if ($opt =~ m/^[A-Z]/) {
@@ -63,6 +69,23 @@ sub unkopt ($$) {
     }
 }
 
+my $display_cmp = \&total_history_cmp;
+my $for_compare = 0;
+
+while (@ARGV && $ARGV[0] =~ m/^\-/) {
+    $_ = shift @ARGV;
+    if (m/^--$/) {
+	last;
+    } elsif (m/^--sort=alpha$/) {
+	$display_cmp = sub { $b->{Cand} cmp $a->{Cand} };
+    } elsif (m/^--for-compare$/) {
+	$for_compare = 1;
+	unshift @ARGV, '--sort=alpha';
+    } else {
+	die;
+    }
+}
+
 for (;;) {
     $_ = <>;
     if (m/^\| /) {
@@ -156,9 +179,33 @@ sub sortballots (@) {
     }
 }
 
+sub floor ($) {
+    my ($v) = @_;
+    $v = new Math::BigRat $v; # we need a copy
+    return $v->bfloor();
+}
+
+sub sv ($) {
+    my ($in) = @_;
+    my $v = new Math::BigRat $in; # just in case
+    my $intpart = floor($v);
+    my $frac = $v - $intpart;
+    my $good = floor($frac * $F);
+    my $bad = $frac * $F - $good;
+    my $s = sprintf "%7d", $intpart;
+    if ($frac) {
+	$s .= sprintf ".%0${DIGS}d", $good;
+	$s .= sprintf "%-4s", ($bad ? "+$bad" : "");
+    } else {
+	$s .= sprintf " %${DIGS}s%4s", '', '';
+    }
+#print STDERR "# $in => $s # (intpart=$intpart frac=$frac)\n";
+    return $s;
+}
+
 sub prf {
     my $fmt = shift;
-    printf "stage %d: ".$fmt, $stage, @_;
+    printf " ".$fmt, @_;
 }
 
 sub countballots () {
@@ -170,17 +217,18 @@ sub countballots () {
 	$c->{History}[$stage-1] = $c->{Total};
     }
 
-    foreach my $c (reverse sort total_history_cmp
+    foreach my $c (reverse sort $display_cmp
 		   grep { !$_->{NonCont} } values %cands) {
-	prf "candidate %-10s: %10s votes\n", $c->{Cand}, $c->{Total};
+	prf "candidate %-10s: %s votes\n", $c->{Cand}, sv $c->{Total};
     }
 }
 
 sub computequota () {
     my $totalvalid = 0/1;
     $totalvalid += $_->{Total} foreach values %cands;
-    $quota = ($totalvalid / (1 + $seats)) -> bfloor();
-    prf "quota %10s\n", $quota;
+    $quota = floor($totalvalid / (1 + $seats) + 1);
+    prf "total valid %s\n", sv $totalvalid;
+    prf "quota       %s\n", sv $quota;
 }
 
 sub total_history_cmp () {
@@ -261,22 +309,29 @@ sub elect_core ($) {
     my ($c) = @_;
     prf "*** ELECT %s \`%s' ***\n", $c->{Cand}, $c->{Desc};
     $c->{NonCont} = 'Elected';
+    push @elected, $c;
 }
 
 $stage = 0;
 
 for (;;) {
     $stage++;
+    printf "stage %3d:\n", $stage;
 
     sortballots @allvotes if $stage == 1;
 
-    my $seats_remain = $seats
-	- grep { ($_->{NonCont} // '') eq 'Elected' } values %cands;
+    my $seats_remain = $seats - @elected;
+
+    prf "seats remaining %d\n", $seats_remain;
+
+    last unless $seats_remain;
+
     if (continuing() <= $seats_remain) {
 	foreach my $c (continuing()) {
 	    prf "electing %s to fill remaining place(s)\n", $c->{Cand};
 	    elect_core $c;
 	}
+	countballots() if $for_compare;
 	last;
     }
 
@@ -301,18 +356,19 @@ for (;;) {
 	    next;
 	}
 
+	last if $seats_remain == 1; # don't bother doing more transfers
+
 	my $B = $c->{Total};
 	my %tspr;
 
-	prf "surplus %10s\n", $surplus;
+	prf "surplus %s\n", sv $surplus;
 
 	foreach my $v (@{ $c->{Votes} }) {
 	    my $previously = $v->{TransferredSurplus};
 	    push @$previously, $c->{Cand};
 
 	    my $A = $surplus * $v->{Weight};
-	    my $F = 100000;
-	    my $xfervalue = ((($A * $F) / $B) -> bfloor() ) / $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)";
@@ -322,8 +378,8 @@ for (;;) {
 		die unless $tspr{"@$previously"} == $xfervalue;
 	    } else {
 		$tspr{"@$previously"} = $xfervalue;
-		prf "transfer value of ballots %s: %10s\n",
-		    "@$previously", $xfervalue;
+		prf "transfer value of ballots %20s: %s\n",
+		    "@$previously", sv $xfervalue;
 	    }
 	}
 	sortballots @{ $c->{Votes} };
@@ -349,4 +405,17 @@ for (;;) {
     die;
 }
 
-print "done.\n"; 
+print "Winners:\n"; 
+
+if ($for_compare) {
+    foreach my $c (sort { $a->{Cand} cmp $b->{Cand} } @elected) {
+	printf "  %s\n", $c->{Cand};
+    }
+} else {
+    foreach my $i (0..$#elected) {
+	my $c = $elected[$i];
+	printf " %3d. %-10s %s\n", $i+1, $c->{Cand}, $c->{Desc};
+    }
+}
+
+print "done.\n";