Module nowcastlib.gis
Functions for computing metrics related to Geographical information science.
Expand source code
"""
Functions for computing metrics related to Geographical information science.
"""
import numpy as np
def great_circle_distance(point_a, point_b, circle_radius):
"""
Calculates the gcd (https://en.wikipedia.org/wiki/Great-circle_distance) between two
points on a sphere.
Parameters
----------
point_a : tuple of float
(lat_a, lon_a) -- tuple specifying latitude and longitude
point_b : tuple of float
(lat_b, lon_b) -- tuple specifying latitude and longitude
circle_radius : float
The radius of the circle upon which the points are.
Returns
-------
float
The great circle distance between the two points
"""
lat_a, lon_a = np.deg2rad(point_a)
lat_b, lon_b = np.deg2rad(point_b)
delta_lon = lon_b - lon_a
central_angle = np.arccos(
np.sin(lat_a) * np.sin(lat_b)
+ np.cos(lat_a) * np.cos(lat_b) * np.cos(delta_lon)
)
return circle_radius * central_angle
def initial_bearing(point_a, point_b):
"""
Calculates the initial bearing (also known as forward azimuth) from point_a to point_b
Parameters
----------
point_a : tuple of float
(lat_a, lon_a) -- tuple specifying latitude and longitude
point_b : tuple of float
(lat_b, lon_b) -- tuple specifying latitude and longitude
Returns
-------
float
The initial bearing in radians
"""
lat_a, lon_a = np.deg2rad(point_a)
lat_b, lon_b = np.deg2rad(point_b)
delta_lon = lon_b - lon_a
return np.arctan2(
np.sin(delta_lon) * np.cos(lat_b),
np.cos(lat_a) * np.sin(lat_b)
- np.sin(lat_a) * np.cos(lat_b) * np.cos(delta_lon),
)Functions
def great_circle_distance(point_a, point_b, circle_radius)-
Calculates the gcd (https://en.wikipedia.org/wiki/Great-circle_distance) between two points on a sphere.
Parameters
point_a:tupleoffloat- (lat_a, lon_a) – tuple specifying latitude and longitude
point_b:tupleoffloat- (lat_b, lon_b) – tuple specifying latitude and longitude
circle_radius:float- The radius of the circle upon which the points are.
Returns
float- The great circle distance between the two points
Expand source code
def great_circle_distance(point_a, point_b, circle_radius): """ Calculates the gcd (https://en.wikipedia.org/wiki/Great-circle_distance) between two points on a sphere. Parameters ---------- point_a : tuple of float (lat_a, lon_a) -- tuple specifying latitude and longitude point_b : tuple of float (lat_b, lon_b) -- tuple specifying latitude and longitude circle_radius : float The radius of the circle upon which the points are. Returns ------- float The great circle distance between the two points """ lat_a, lon_a = np.deg2rad(point_a) lat_b, lon_b = np.deg2rad(point_b) delta_lon = lon_b - lon_a central_angle = np.arccos( np.sin(lat_a) * np.sin(lat_b) + np.cos(lat_a) * np.cos(lat_b) * np.cos(delta_lon) ) return circle_radius * central_angle def initial_bearing(point_a, point_b)-
Calculates the initial bearing (also known as forward azimuth) from point_a to point_b
Parameters
point_a:tupleoffloat- (lat_a, lon_a) – tuple specifying latitude and longitude
point_b:tupleoffloat- (lat_b, lon_b) – tuple specifying latitude and longitude
Returns
float- The initial bearing in radians
Expand source code
def initial_bearing(point_a, point_b): """ Calculates the initial bearing (also known as forward azimuth) from point_a to point_b Parameters ---------- point_a : tuple of float (lat_a, lon_a) -- tuple specifying latitude and longitude point_b : tuple of float (lat_b, lon_b) -- tuple specifying latitude and longitude Returns ------- float The initial bearing in radians """ lat_a, lon_a = np.deg2rad(point_a) lat_b, lon_b = np.deg2rad(point_b) delta_lon = lon_b - lon_a return np.arctan2( np.sin(delta_lon) * np.cos(lat_b), np.cos(lat_a) * np.sin(lat_b) - np.sin(lat_a) * np.cos(lat_b) * np.cos(delta_lon), )