Script to fix distance for indoor cycling activities in TCX files exported from Garmin Connect

distancefix.py

import argparse
import datetime
import xml.etree.ElementTree as ET

# To do: should set this up dynamically from the xmlns in the file
ns = {'tcx' : "http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2"}
time_format = '%Y-%m-%dT%H:%M:%S.000Z'

parser = argparse.ArgumentParser(description = "Recalculate distance in TCX file for indoor activities")
parser.add_argument("file", type = argparse.FileType('r'), help = "Input TCX file")
parser.add_argument("distance", type = int, help = "Distance in meters")

args = parser.parse_args()

# print(args)

tree = ET.parse(args.file)
activities = tree.getroot().find('tcx:Activities', ns)
activity = activities.find('tcx:Activity', ns)
lap = activity.find('tcx:Lap', ns)

start_time = datetime.datetime.strptime(lap.attrib['StartTime'], time_format)
duration = datetime.timedelta(seconds = float(lap.find('tcx:TotalTimeSeconds', ns).text))

end_time = start_time + duration

lap_distance = lap.find('tcx:DistanceMeters', ns)
lap_distance.text = str(args.distance)

track = lap.find('tcx:Track', ns)
trackpoints = track.findall('tcx:Trackpoint', ns)

for point in trackpoints:
    current_time = datetime.datetime.strptime(point.find('tcx:Time', ns).text, time_format)
    current_duration = current_time - start_time
    duration_completed = current_duration / duration
    
    distance_so_far = point.find('tcx:DistanceMeters', ns)
    distance_so_far.text = str(duration_completed * args.distance)

tree.write('out.tcx')