gx:Track not supported

[hyperknot]

fastkml doesn't support gx:Track geometries.

what happens is that kml.py / Placemark / from_element method cannot detect a {http://www.google.com/kml/ext/2.2}Track element, thus arrives at No geometries found error.

sample file (saved with latest Google Earth):
https://gist.github.com/hyperknot/32ac836881b760aa3d02cc24d01a7dfd

[scls19fr]

Hello,

I was looking for a similar feature.
I have a KML file with gx:Track, altitudeMode, when, gx:coord tags (see reference) and was expecting a way to use fastkml to iterate over positions... but I doesn't seems to be currently possible.

I will directly parse KML file using lxml or ElementTree but maybe a first step for supporting such features in this library could be that fastkml.kml.Placemark could hold simply xml elements as more "low level" lxml objects (ie using ElementTree API).

Kind regards

In [1]: from fastkml import kml

In [2]: fname = "sample.kml"

In [3]: k = kml.KML()

In [4]: with open(fname, 'rb') as fd:
   ...:     doc = fd.read()
   ...:     k.from_string(doc)
   ...:
No geometries found

In [5]: features = list(k.features())

In [6]: p = features[0]

[scls19fr]

Here is some "low level" code using ElementTree

import xml.etree.ElementTree as ET
import datetime
from collections import namedtuple

Position = namedtuple("Position", ["dt", "longitude", "latitude", "altitude"])


def read_kml_track(fname):
    tree = ET.parse(fname)
    root = tree.getroot()
    ns = {
        "kmlns": "http://www.opengis.net/kml/2.2",
        "gx": "http://www.google.com/kml/ext/2.2",
    }
    track_elements = root.find("kmlns:Placemark/gx:Track", namespaces=ns)
    dt = None
    for elt in track_elements:
        tag = elt.tag
        if tag == "{%s}when" % ns["kmlns"]:
            dt = datetime.datetime.strptime(elt.text, "%Y-%m-%dT%H:%M:%S%z")
        elif tag == "{%s}coord" % ns["gx"]:
            s = elt.text
            longitude, latitude, altitude = s.replace(",", ".").split()
            longitude, latitude, altitude = map(float, (longitude, latitude, altitude))
            yield Position(dt, longitude, latitude, altitude)


fname = "sample.kml"
positions = read_kml_track(fname)
for p in positions:
    print(p)

I'm just pasting here if some people need a similar feature.

Not sure if my code can work with @hyperknot sample file.

[scls19fr]

This code also work with @hyperknot sample file

import xml.etree.ElementTree as ET
import datetime
from collections import namedtuple

Position = namedtuple("Position", ["dt", "longitude", "latitude", "altitude"])


def read_kml_track(fname):
    tree = ET.parse(fname)
    root = tree.getroot()
    ns = {
        "kmlns": "http://www.opengis.net/kml/2.2",
        "gx": "http://www.google.com/kml/ext/2.2",
    }
    # track_elements = root.find("kmlns:Placemark/gx:Track", namespaces=ns)
    track_elements = root.find("kmlns:Document/kmlns:Placemark/gx:Track", namespaces=ns)
    lst_when = track_elements.findall("kmlns:when", namespaces=ns)
    lst_coord = track_elements.findall("gx:coord", namespaces=ns)
    for when, coord in zip(lst_when, lst_coord):
        dt = datetime.datetime.strptime(when.text, "%Y-%m-%dT%H:%M:%S%z")
        s = coord.text
        longitude, latitude, altitude = s.replace(",", ".").split()
        longitude, latitude, altitude = map(float, (longitude, latitude, altitude))
        yield Position(dt, longitude, latitude, altitude)


# fname = "sample.kml"
fname = "gx_track.kml"
positions = read_kml_track(fname)
for p in positions:
    print(p)