longlat.py

#helper function to estimate long/lat range based on long/lat and range in km
def calc_longlat_range(longitude, latitude, range_km):
    from math import cos, radians, pi
    r = 6370
    alpha = radians(latitude)
    circum = 2 * pi * cos(alpha) * r

    km_per_long = circum / 360
    km_per_lat = pi * r / 180

    result = dict()
    result["lat_range"] = range_km / km_per_lat
    result["long_range"] = range_km / km_per_long

    return result