Extracting specific track segments from a track
I have an i-Blue 747A+ GPS logger which I use to track my runs (amongst other things). Afterwards I use BT747 to retrieve the data from the device and create a GPX file of the run, which I then upload to Endomondo which gives me nice graphs and statistics.
I need to modify the GPX file slightly before I can do so however: I use the button on the device to mark the beginning and end of the run, which appear as waypoints in the GPX file. BT747 creates separate track segments (within a single track) between each waypoint, but Endomondo ignores these. I therefore need to extract the single track segment covering the actual run and create a new GPX file with just that segment. I therefore wrote a script in Python, splittrack.py, to do this. It uses the gpxdata library to parse the input file, locates any track segment which match a set of time, distance, displacement and speed criteria1, and outputs a new GPX file with just those.
Integrating heart rate data
I then recently bought an Oregon Scientific WM100 heart rate logger. It listens to the broadcasts from a heart rate strap2 and records the measurements every 2 seconds. I retrieve the data using the wm100 driver for Linux which writes a CSV file like this:
In order to get this data into Endomondo, I needed to combine the GPS trace with the HRM data into a single file format which Endomondo accepts. I initially started implementing a library for the TCX format3, but then discovered that there is a GPX extension for including heart rata data which Endomondo accepts. So I wrote a script in Python, wm100gpx.py, which reads the input GPX and CSV files, merges the heart rate measurements into the GPX records, and outputs a new GPX file.
The entries look like this:
<trkpt lat="37.392051" lon="-122.090240"> <ele>-44.400761</ele> <time>2012-10-15T01:20:13Z</time> <extensions> <gpxtpx:TrackPointExtension> <gpxtpx:hr>175</gpxtpx:hr> </gpxtpx:TrackPointExtension> </extensions> </trkpt>