Initial commit

README.md

+# kmljoin
+
+Join multiple KML files into a single KML file. One `gx:Track` per file and all `gx:SimpleArrayData`s will be merged.**
+
+# Expected format
+
+This was written to handle Foreflight track logs, which look something like this.
+
+```xml
+<?xml version="1.0" encoding="UTF-8"?>
+<kml xmlns="http://www.opengis.net/kml/2.2"  xmlns:gx="http://www.google.com/kml/ext/2.2">
+ <Document>
+  <open>1</open>
+  <visibility>1</visibility>
+  <Style id="trackStyle"><LineStyle>,<PolyStyle>...</Style>
+  <Placemark>
+   <name></name>
+   <gx:Track>
+    <altitudeMode>absolute</altitudeMode>
+    <extrude>1</extrude>
+    <gx:interpolate>1</gx:interpolate>
+    <when>...</when>
+    <gx:coord>....</gx:coord>
+    <when>...</when>
+    <gx:coord>....</gx:coord>
+    <when>...</when>
+    <gx:coord>....</gx:coord>
+   </gx:Track>
+  </Placemark>
+  <Placemark><name>Start</name><Point><coordinates>...</coordinates></Point></Placemark>
+  <ExtendedData>
+   <SchemaData>
+    <gx:SimpleArrayData name="acc_horiz"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="acc_vert"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="course"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="speed_kts"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="altitude"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="bank"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+    <gx:SimpleArrayData name="pitch"><gx:value>0</gx:value>...</gx:SimpleArrayData>
+   </SchemaData>
+   <Data name="source"><displayName>Source</displayName><value>ForeFlight Web</value></Data>
+   <Data name="GPSModelName"><value>Stratus</value></Data>
+   <Data name="flightTitle"><value></value></Data>
+   <Data name="pilotName"><value></value></Data>
+   <Data name="tailNumber"><value></value></Data>
+   <Data name="pilotNotes"><value></value></Data>
+  </ExtendedData>
+ </Document>
+</kml>
+```

kmljoin.py

+#!/bin/env python3
+"""kmljoin - Join multiple KML files into a single KML file."""
+
+# Missing features:
+#  - Warn about large temporal discontinuity between files
+#  - Combine distinct airports/waypoint names for title
+
+
+import copy
+import sys
+import xml.etree.ElementTree as ET
+
+
+XML_NS = {
+    '': 'http://www.opengis.net/kml/2.2',
+    'gx': 'http://www.google.com/kml/ext/2.2',
+}
+
+ET.register_namespace('', 'http://www.opengis.net/kml/2.2')
+ET.register_namespace('gx', 'http://www.google.com/kml/ext/2.2')
+
+def combine_files(kml_files):
+    """Combine two or more KML files into one."""
+    if not kml_files or len(kml_files) < 2:
+        raise(Exception('Two or more KML files required.'))
+    (first_kml_etree, first_track, first_arrays) = _read_file(kml_files[0])
+    for kml_file in kml_files[1:]:
+        (kml_etree, track, arrays) = _read_file(kml_file)
+        # concatenate Tracks
+        for track_node in track:
+            if track_node.tag in (f'{{{XML_NS[""]}}}when', f'{{{XML_NS["gx"]}}}coord'):
+                first_track.append(copy.deepcopy(track_node))
+        # concatenate SimpleArrayData arrays
+        for name, array in arrays.items():
+            if name in first_arrays:
+                for array_node in array:
+                    first_arrays[name].append(copy.deepcopy(array_node))
+            else:
+                first_arrays[name] = array
+    return first_kml_etree
+
+
+def _read_file(kml_file):
+    """Parse a KML file and return the ETree, Track, and SimpleArrayData lists."""
+    kml_etree = ET.parse(kml_file)
+
+    def _get_arrays(kml_etree):
+        """Extract all SimpleArrayData lists."""
+        arrays = kml_etree.findall(".//gx:SimpleArrayData", XML_NS)
+        return {a.get('name'): a for a in arrays}
+
+    def _get_track(kml_etree):
+        """Extract one gx:Track."""
+        tracks = kml_etree.findall(f".//gx:Track", XML_NS)
+        if not tracks:
+            raise(Exception('No tracks found.'))
+        if len(tracks) > 1:
+            raise(Exception('Cannot handle multiple tracks.'))
+        return tracks[0]
+
+    return kml_etree, _get_track(kml_etree), _get_arrays(kml_etree)
+
+if __name__ == '__main__':
+    kml_files = sys.argv[1:]
+    try:
+        combined_etree = combine_files(kml_files)
+        ET.dump(combined_etree)
+    except Exception as e:
+        print('Error: {}'.format(e))
+