tcx_dist.py

#!/usr/bin/env python
# Usage: ./tcx_dist.py [input.tcx] [new distance in meters]
# Override distance of track points in TCX with new overall distance

from time import strptime, strftime
import xml.etree.ElementTree as ET
import sys
import re

infile = open(sys.argv[1])
new_dist = float(sys.argv[2])
if new_dist < 50:
    new_dist = new_dist * 1609.34

def get_time(e):
    timestamp = e.find('{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}Time').text
    return int(strftime('%s', strptime(timestamp, '%Y-%m-%dT%H:%M:%S.000Z')))

ET.register_namespace('', "http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2")

tcx = ET.fromstring(infile.read())

activity = tcx.find('.//{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}Activity').attrib['Sport']

start_seconds = get_time(tcx.findall('.//{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}Trackpoint')[0])
end_seconds = get_time(tcx.findall('.//{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}Trackpoint')[-1])
total_seconds = end_seconds - start_seconds

for point in tcx.findall('.//{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}Trackpoint'):
    seconds = get_time(point)
    percent = (seconds - start_seconds) / total_seconds
    dist_fixed = new_dist * percent
    point.find('{http://www.garmin.com/xmlschemas/TrainingCenterDatabase/v2}DistanceMeters').text = str(dist_fixed)

with open('out.tcx', 'w') as f:
    f.write('<?xml version="1.0" encoding="UTF-8"?>\n')
    f.write(ET.tostring(tcx, encoding='unicode'))