Concatenate track segments of multiple .gpx files into one

concatgpx.py

#!/usr/bin/env python
##
## Concatenate track segments of multiple .gpx files into one.
##
## Usage: python concatgpx.py [input1] [input2] [...] > [output]
##
## If the first .gpx file contains more than one <trkseg>, then the output file will contain a <trk> element
## with multiple <trkseg> child elements appended from the subsequent input files. If there is only a single
## <trkseg> element in the first input file, then the output file will contain a <trk> element with a single
## <trkseg> element containing all the <trkpt> elements from the subsequent input files.
##
import sys
import xml.etree.ElementTree as ElementTree

ns = { 'gpx': 'http://www.topografix.com/GPX/1/1' }
ElementTree.register_namespace('', ns['gpx'])

output = None
append_segments = False

for source in sys.argv[1:]:
    tree = ElementTree.parse(source)
    if output is None:
        output = tree
        append_segments = len(tree.findall('./gpx:trk/gpx:trkseg', ns)) > 1
        continue
    if append_segments:
        root = output.find('./gpx:trk', ns)
        map(root.append, tree.findall('./gpx:trk/gpx:trkseg', ns))
    else:
        root = output.find('./gpx:trk/gpx:trkseg', ns)
        map(root.append, tree.findall('./gpx:trk/gpx:trkseg/gpx:trkpt', ns))

if output:
    output.write(sys.stdout, encoding='utf-8', xml_declaration=True)