Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

Support samples along a path

See original GitHub issue

The google maps api lets you sample along a path. I don’t have plans to support this any time soon in Open Topo Data, but a user submitted a patch for v1.5.0 to add this functionality!

Update 2021-09-04: The patch below has some issues, here’s a better method that I’m adding: Sampling points along a lat,lon path

Old patch

--- opentopodata.orig/api.py	2021-03-10 16:36:58.761755648 +0100
+++ opentopodata/api.py	2021-03-21 09:43:48.369460334 +0100
@@ -190,6 +190,44 @@
         return _parse_polyline_locations(locations, max_n_locations)
 
 
+def _create_path_with_samples(lats, lons, samples):
+    """Create a path with the requested samples starting from given path
+
+
+    Args:
+        lats: The latitudes
+        lons: The longitudes
+        samples: Number of point in the segments of the path.
+
+    Returns:
+        lats: List of latitude floats.
+        lons: List of longitude floats.
+    """
+
+    if(len(lats) < 2):
+        return lats, lons
+    if(int(samples) < 2):
+        samples = 2;
+    lats1 = []
+    lons1 = []
+    lat1 = lats[0]
+    lon1 = lons[0]
+    for i in range(1, len(lats)):
+        lat2 = lats[i]
+        lon2 = lons[i]
+        dlat = (lat2 - lat1) / (int(samples) - 1)
+        dlon = (lon2 - lon1) / (int(samples) - 1)
+        lat = lat1
+        lon = lon1
+        for i in range(0, int(samples)):
+            lats1.append(lat)
+            lons1.append(lon)
+            lat += dlat
+            lon += dlon
+
+    return lats1, lons1
+
+
 def _parse_polyline_locations(locations, max_n_locations):
     """Parse and validate locations in Google polyline format.
 
@@ -399,6 +437,11 @@
             request.args.get("locations"), _load_config()["max_locations_per_request"]
         )
 
+        samples = request.args.get("samples")
+        if not samples:
+            samples = 2
+        lats, lons = _create_path_with_samples(lats, lons, samples)
+
         # Get the z values.
         datasets = _get_datasets(dataset_name)
         elevations, dataset_names = backend.get_elevation(