This query function will calculate the distance, in meters,
between two geographical coordinates
(lat1,
lon1) and
(lat2,
lon2) along an ideal earth
surface.
It uses the Haversine approximation, which is accurate to about
0.5%. It does not take the altitude into account.
In this example, the geography:distance() function
is used to calculate the distance in meters between London and Tokyo
using geographical coordinates.
Note that the values of latitude and longitude coordinates must be
expressed in decimal degrees.
Calculates the distance between two points on Earth (in this example,
London and Tokyo) given their latitude and longitude, and returns the
result in a field named
distance. By default, the
distance is returned in meters.
Using the eval() function, it is possible to
convert the result to kilometers for easier interpretation by adding
the following to the query: |
eval(_distanceKm = distance / 1000). This will return the
results in a field named
_distanceKm.
Event Result set.
Summary and Results
The query is used to calculate the distance between two geographical
coordinates (lat1,
lon1) and
(lat2,
lon2) along an ideal earth surface.
In this example, the parameters
lat1 and
lon1 are the
coordinates of the first point (London), and the parameters
lat2 and
lon2 are the
coordinates of the second point (Tokyo).
Sample output from the incoming example data:
distance
londonLat
londonLon
tokyoLat
tokyoLon
9558729.514524894
51.507222
-0.1275
35.689722
139.692222
Sample output from the incoming example data when converted to
kilometers:
londonLat
londonLon
tokyoLat
tokyoLon
_distanceKm
51.507222
-0.1275
35.689722
139.692222
9558.73 km
Geographical calculations can be useful in log analysis involving
location data, network traffic analysis across global infrastructure, or
any scenario where geographical distance is relevant.
