plot run data of Garmin Forerunner using gnuplot

extract.pl

#!/usr/bin/perl

# untouched version originally found on <http://ww.telent.net/tmp/extract.pl> and <http://ww.telent.net/tmp/png.gp>
# <https://web.archive.org/web/20100928045039/http://www.coruskate.net/Garmin%20and%20Linux>

use strict;
use warnings;
use Getopt::Long;
use Math::Trig;
my $pi=2*acos(0);

my $basedir=$ENV{HOME}."/training";
chdir($basedir);

sub speed {
    my($old,$new)=@_;
    my ($lon0,$lat0)=(@{$old}[2],@{$old}[1]);
    my ($lon1,$lat1)=(@{$new}[2],@{$new}[1]);
    my $scale=cos($pi * (($lat0+$lat1) / 360));
    my ($dx,$dy)=(111000*($lat1-$lat0),
		  $scale*111000*($lat1-$lat0));
    return 3.6 *((sqrt($dx*$dx+$dy*$dy))/(($new->[0]) - ($old->[0])));
}


my ($start,$end);
GetOptions ("start=i" => \$start,
	    "end=i"   => \$end);

my %segments;
my $gap=$start ? int($start/600) : 0;

@ARGV=glob("linuxDataExport/*");
while(<>) {
    my($time,$lat,$lon,$alt,$hr)=split(/,/);
    next if($time =~ /[^\d]/);
    my $r=int($time/600);
    $segments{$r}++;
}
my ($prev,$len)=(0,0);
$start || print "No --start argument: choose from:\n";

foreach  my $k(sort keys %segments) {
    my $s=600*$k;
    if($prev==($k-1)) {
	($gap==$prev) && $gap++;
	$len+=10;
    } else {
	unless($start) {
	    if($len) { 	print "($len minutes)\n";  }
	    print " ".(scalar localtime $s)." : $s ";
	}
	$segments{$k}=$len;
	$len=10;
    }
    $prev=$k;
}
if(!$start) {
    $len && print "($len minutes)\n";
    exit 0;
}
unless($end) {
    $end=(1+$gap)*600;
}
$ENV{OUTNAME}="$start-$end";

open(GP,">/tmp/extract.gp") or die "extract.gp: $!";
open(DAT,">/tmp/f.$$.dat") or die "f.$$.dat: $!";
my @old;
@ARGV=glob("linuxDataExport/*");
while(<>) {
    chomp;
    my @f=split(/,/);
    next if($f[0] =~ /[^\d]/);
    @old=(1,@f[1..10]) unless(@old) ;
    my $speed=speed(\@old,\@f);
    if(($f[0]>=$start) && ($f[0]<=$end)) {
	print DAT "".($f[0]-$start)." ".$f[4]." $speed\n";
    }
    @old=@f;
}
my $title=scalar localtime $start;
print GP <<CONTROL
set yrange [80:180] 
set y2range [0:50]   
set y2tics 10
set ylabel "bpm"
set y2label "km/h"
set xlabel "Time (s)"
set title "$title"
plot "/tmp/f.$$.dat"  using 1:3 axes x1y2 title "km/h" with lines, "" using 1:2 with lines title "HR"
set term png size 400,200 
set output "/tmp/graph-small.png"
replot
set term png size 1000,400 
set output "/tmp/graph-big.png"
replot
set term x11
CONTROL
    ;
close(GP);
system("gnuplot /tmp/extract.gp -");

png.gp

set term png size 400,200 
set output "|cat >$OUTNAME-small.png"
replot
set term png size 1000,400 
set output "|cat >$OUTNAME-big.png"
replot
set term x11