Center Geolocations

center_geo.py

from math import cos, sin, atan2, sqrt

def center_geolocation(geolocations):
    """
    Provide a relatively accurate center lat, lon returned as a list pair, given
    a list of list pairs.
    ex: in: geolocations = ((lat1,lon1), (lat2,lon2),)
        out: (center_lat, center_lon)
    """
    x = 0
    y = 0
    z = 0

    for lat, lon in geolocations:
        lat = float(lat)
        lon = float(lon)
        x += cos(lat) * cos(lon)
        y += cos(lat) * sin(lon)
        z += sin(lat)

    x = float(x / len(geolocations))
    y = float(y / len(geolocations))
    z = float(z / len(geolocations))

    return (atan2(z, sqrt(x * x + y * y)), atan2(y, x))

lhejazi is correct; the function returns the results the wrong way round as long, lat - this is easily checked by putting a single set of lat, long coordinates through the function

been a few years since I looked at this, thank you for the reminder I've updated the gist

I don't think this works well. For example:

center_geolocation([(56.012, -3.61), (56.016, -3.62)])

returns: (-0.5346732451559053, 2.6681793850777766)

That makes no sense to me. I would expect something like (56.014, -3.615), or is my thinking wrong?

I think you’ve programmed something incorrectly. The attached is my implementation of this algorithm which allows one to weight the calculation of the average long and lat by an area; this returns the expected result. Adam On 2 Mar 2020, at 14:32, Firzen7 <notifications@github.com<mailto:notifications@github.com>> wrote: I don't think this works well. For example: center_geolocation([(56.012, -3.61), (56.016, -3.62)]) returns: (-0.5346732451559053, 2.6681793850777766) That makes no sense to me. I would expect something like (56.014, -3.615), or is my thinking wrong? — You are receiving this because you commented. Reply to this email directly, view it on GitHub<https://gist.github.com/3718961?email_source=notifications&email_token=AMUNGVRKHEJDUSI6IY2CBULRFO7O5A5CNFSM4IEQKRHKYY3PNVWWK3TUL52HS4DFVNDWS43UINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQAGDCTC#gistcomment-3196209>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AMUNGVVXTWDLITBCNPI43Z3RFO7O5ANCNFSM4IEQKRHA>.

@AdamEyreWalker I am not sure, because I haven't programmed anything :D Steps I did:

1. Select contents of center_geo.py
2. Go to https://repl.it/languages/python3
3. Paste source code in the editor
4. Click run
5. Input center_geolocation([(56.012, -3.61), (56.016, -3.62)]) in the console
6. Press ENTER

As I said, I didn't change anything. :-)

I’m not sure whats happening then, because it works for me. It just might be a difference between Python2 and Python3 but I doubt it. Sorry I can’t be of more help. Adam On 3 Mar 2020, at 12:36, Firzen7 <notifications@github.com<mailto:notifications@github.com>> wrote: @AdamEyreWalker<https://github.com/AdamEyreWalker> I am not sure, because I haven't programmed anything :D Steps I did: 1. Select contents of center_geo.py 2. Go to https://repl.it/languages/python3<https://repl.it/languages/python3> 3. Paste source code in the editor 4. Click run 5. Input center_geolocation([(56.012, -3.61), (56.016, -3.62)]) in the console 6. Press ENTER As I said, I didn't change anything. :-) — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub<https://gist.github.com/3718961?email_source=notifications&email_token=AMUNGVVRQC2SCBCWPTUR7P3RFT2UPA5CNFSM4IEQKRHKYY3PNVWWK3TUL52HS4DFVNDWS43UINXW23LFNZ2KUY3PNVWWK3TUL5UWJTQAGDFZ4#gistcomment-3197854>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AMUNGVUOLILEHRTLB4VIXYDRFT2UPANCNFSM4IEQKRHA>.

@AdamEyreWalker @Firzen7 You have to convert to radians first, this funcion assumes input is in radians:
lat_rad = latPi/180
lon_rad = lonPi/180

just convert it back to degrees at the end