calculate distance from GPX file

gpx_distance.py

#!/usr/bin/python

from osgeo import ogr
from osgeo import osr
import xml.sax
import xml.sax.handler
import sys

class Handler(xml.sax.handler.ContentHandler):
	def __init__(self):
		self.result = []

	def startElement(self, name, attrs):
		self.last_element = name
		if(name=='trkpt'):
			self.pos = attrs

	def characters(self, content):
		if(self.last_element == 'ele'):
			self.ele = content
		elif(self.last_element == 'time'):
			self.time = content

	def endElement(self, name):
		if(name=='trkpt'):
			point = ogr.Geometry(ogr.wkbPoint)
			point.AddPoint(float(self.pos['lon']), float(self.pos['lat']))
			self.result.append({'time':self.time,'pos': point})
		elif(name=='gpx'):
			self.result = tuple(self.result)

def read_data(filename=sys.stdin):
	handler = Handler()
	parser = xml.sax.make_parser()
	parser.setContentHandler(handler)
	
	parser.parse(filename)
	return handler.result

def main(args):
	if(len(args) > 1):
		data = read_data(args[1])
	else:
		data = read_data(sys.stdin)

	source = osr.SpatialReference()
	source.ImportFromEPSG(4326)
	target = osr.SpatialReference()
	target.ImportFromEPSG(6677)

	line = ogr.Geometry(ogr.wkbLineString)
	ct = osr.CreateCoordinateTransformation(source,target)
	for i in data:
		p = i['pos']
		p.Transform(ct)
		line.AddPoint(p.GetX(), p.GetY())

	print line.Length()

if(__name__=='__main__'):
	main(sys.argv)