This is not a class assignment but a conceptual question I’m struggling with for a personal project.
I need to convert a large paired group of long and lat coordinate values that show a two-dimensional directional change to degrees change (0-360).
What are the fastest ways to make this kind of transformation? I am hoping to avoid nesting a lot of conditional statements.
8
For accuracy better than the general tools use to gather the data is a Python module pyproj Feed your data into something like the odometer function extracted from waypoint.py
from pyproj import Geod # sudo pip3 install pyproj
geoid = Geod(ellps='WGS84') # See pyproj documentation for other fun options
def odometer(start, end):
"""Calculate bearings and distance between start and end.
Arguments:
start (tuple of float): latitude and longitude of starting position
end (tuple of float): latitude and longitude of ending position
Returns:
float: True North bearing start -> end
float: True North bearing end -> start
float: distance start <-> end in meters
"""
try:
bearing_to, bearing_fro, distance = geoid.inv(*start + end)
except Exception as error: # more specific?
print("odometer({}, {}) created error:{}".format(start, end, error))
return None
bearing_to %= 360
bearing_fro %= 360
return bearing_to, bearing_fro, distance
I used geographiclib to find the azymouth (0 – 360) between 2 points in the WGS84 ellipsoid using the Inverse method and filtering its results as follows:
from geographiclib.geodesic import Geodesic
def orientation(startpoint, endpoint): # each point is a tuple of (lon, lat)
return (
Geodesic.WGS84.Inverse(
startpoint[1],
startpoint[0],
endpoint[1],
endpoint[0],
)['azi1'] % 360
)
The degrees can be converted to directions based on the compass points. Here is a more clean approach.
I have used the following code and verified some results with this online service:
from geographiclib.geodesic import Geodesic
def orientation(startpoint, endpoint): # each point is a tuple of (lon, lat)
azi = (
Geodesic.WGS84.Inverse(
startpoint[1],
startpoint[0],
endpoint[1],
endpoint[0],
)['azi1'] % 360
)
ranges = {
(0, 11.25): 'N',
(11.25, 33.75): 'NNE',
(33.75, 56.25): 'NE',
(56.25, 78.75): 'ENE',
(78.75, 101.25): 'E',
(101.25, 123.75): 'ESE',
(123.75, 146.25): 'SE',
(146.25, 168.75): 'SSE',
(168.75, 191.25): 'S',
(191.25, 213.75): 'SSW',
(213.75, 236.25): 'SW',
(236.25, 258.75): 'WSW',
(258.75, 281.25): 'W',
(281.25, 303.75): 'WNW',
(303.75, 326.25): 'NW',
(326.25, 348.75): 'NNW',
(348.75, 360): 'N',
}
for i in ranges.keys():
if i[0] < azi <= i[1]:
return ranges[i]
0