Merge (and possibly rename) GPX files

gpx_merge.py

########
# This code is useful for combining many GPX files, each with a single <trk>, into
# a single GPX file containing one <trk> that has one <trkseg> per input GPX file.
#
# This is necessary for animating GPX files using GPX Animator: https://gpx-animator.app/
########

import shutil
import glob
from datetime import datetime
import gpxpy
import gpxpy.gpx

files = glob.glob('runs/*.gpx')

########
# If you also want to renaming a series of .gpx files based on the 
# name of the first (possibly *only*) track in the gpx file, uncomment this.
# It assumes the date format is like this: '2019-06-02T13:32:41.175Z'.
########
# output_dir = 'revised'
# 
# for f in files:
#     with open(f, 'r') as gpx_file:
#         gpx = gpxpy.parse(gpx_file)
#         datestr = gpx.tracks[0].name[4:-5]
#         new_name = datetime.strptime(datestr, '%Y-%m-%dT%H:%M:%S').strftime('%Y%m%d-%H%M%S')
#         shutil.copyfile(f, f'{output_dir}/{new_name}.gpx')
#         print(f'old: {f} --> new: {output_dir}/{new_name}.gpx')


# create new GPX file, append a blank track
new_gpx = gpxpy.gpx.GPX()
new_track = gpxpy.gpx.GPXTrack()
new_gpx.tracks.append(new_track)

for f in files:
    with open(f, 'r') as gpx_file:
        gpx = gpxpy.parse(gpx_file)
        new_track.segments.append(gpx.tracks[0].segments[0])

with open('merged_runs.gpx', 'w') as f:
    f.write(new_gpx.to_xml())