vpower.py

"""vpower.py. Add power to TCX file for Garmin Tacx Blue Motion indoor trainer

Usage:
  vpower.py [--lever=<lv>] INPUT

Arguments:
  INPUT 		Required .TCX input filename

Options:
  -h --help 	Show this.
  --lever=<lv>	Specify position of the handlebar resistance lever [default: 5].

"""
from __future__ import print_function
import re, sys
from docopt import docopt
# To install docopt: pip install docopt
# To install pip : get get-pip.py from http://www.pip-installer.org/en/latest/installing.html#install-or-upgrade-pip
# python get-ip.py

def s2p(speed, lever=5):
	assert (lever > 0 and lever < 11)
	# The array factor contains power at 60km/h at lever positions 1 to 10
	# Derived from http://www.tacx.com/en/products/trainers/blue-motion#tab_2
	factor =  [200.0,281.0,366.0,447.0,532.0,616.0,702.0,787.0,868.0,953.0]
	return int(speed/60.0*factor[lever-1])

def process(inputfilename, lever):
	with open(inputfilename, 'rt') as fi:
		for line in fi:
			print (line, end='')
			match = re.match('\s+<Speed>(\d+.\d+)',line)
			if match:
				speed = float(match.group(1))
				speed_in_kmperh = speed/1000.0*60.0*60.0
				power_in_watt = s2p(speed_in_kmperh, lever)
				print ('                <Watts>%d</Watts>' % power_in_watt)

if __name__ == '__main__':
    arguments = docopt(__doc__)
    inputfilename = arguments["INPUT"]
    if not inputfilename.endswith('.tcx'):
    	print ("input file %s has no .tcx extention" % inputfilename)
    	exit(-1)
    if arguments['--lever']:
    	lever = int(arguments['--lever'])
    	assert (lever > 0 and lever <11)
    	sys.stderr.write('Handlebar resistance lever position = %d \n' % lever)
    	sys.stderr.flush()
    else:
    	lever = 5
    	sys.stderr.write('Assuming default handlebar resistance lever postion at 5\n')
    	sys.stderr.flush()
    process(inputfilename, lever)