rivers/new.plot.pl

use strict;
use diagnostics;
use DBI;

my $db = DBI->connect("dbi:SQLite:dbname=rivers.db") or die $DBI::errstr;

my $stations_st = $db->prepare("select id, name, watercourse from stations where exclude<>'yes'");
$stations_st->execute();
my $stations = $stations_st->fetchall_hashref("id");

my $watercourses = {};
foreach my $station (keys %{$stations}) {
	push @{$watercourses->{$stations->{$station}->{watercourse}}}, $station;
}

print <<EOF;
set term png medium size 3200,1200 enhanced font "Helvitica" 14

set datafile missing "-"
set xlabel "Date"
set timefmt "%Y-%m-%dT%H:%M"
set format x "%Y-%m-%d"
set xdata time
set xtics autofreq

set ylabel "River level (m)"
set grid y

set key outside bottom center horizontal

set label 11 left at graph 0,char 1 "Data from Environment Agency processed via mafoo.org.uk" font ",12"
EOF

1;

foreach my $watercourse (keys %{$watercourses}) {
	print "\n### $watercourse\n";
	my $file = lc $watercourse;
	$file =~ s~[^\w\d]+~_~g;
	print "set output 'new.out/$file.png'\n";
	print "set title '$watercourse'\n";

	print "plot \\\n";
	my @plots;
	foreach my $stationid (@{$watercourses->{$watercourse}}) {
		push @plots, qq(  "< sqlite3 -init plot.sqliterc rivers.db 'select timestamp, level from levels where stationid = $stationid'" using 1:2 title "$stations->{$stationid}->{name}" with linespoints);
	}

	print join(", \\\n", @plots), "\n";
}