Presentation slide on GeoPy module of Python.

1. GeoPy Module in
Python
MEMBERS:
ASHMITA DHAKAL (07)
ROHIT GAUTAM (09)
PRASHANT THAPALIYA (29)
AAKASH THAPA (31)
1

2. Introduction to ‘geopy’
A module is a file containing Python definitions and statements.
geopy - used for geocoding web services.
A Python 2 and 3 client.
Makes easier to geolocate:
Addresses
Cities
Countries
Landmarks
along with co-ordinates and vice versa.
2

3. geopy and geocoders
geopy provides geolocation across the globe
Uses third-party (i.e. geocoders)
 Uses Google Maps, Bing Maps or Nominatim as geolocation sevices.
Such services has its own class in geopy.geocoders
Each geocoder accepts the required settings or credentials to interact with
services
3

4. Installation of geopy
install geopy in command prompt by :
pip install geopy
4

5. Importing geopy module
In order to use geopy module, the module should be imported.
The module can be imported as:
from geopy import *
from geopy.geocoders import *
NOTE: executing geopy module for geolocation requires fast internet connection.
5

6. Available contents at geopy.geocoders
Baidu
Bing
Nominatim
ArcGIS
What3Words
GoogleV3
Etc.
6

7. Nominatim
Is a search engine
Associated with OpenStreetMap (OSM)
Provision for:
Forward search (coordinate from address)
Reverse search (look for data from coordinates)
7

8. Nominatim
Nomination is used to mention the application name which is used in program
to geolocate the inputs.
Nominatim is a search engine for OpenStreetMap data. This is the debugging
interface.
>>> from geopy.geocoders import Nominatim
>>> geolocator = Nominatim(user_agent=“OSM")
8

9. geopy module methods
Methods are the member of classes.
Use to perform specific task.
 An object method can only have access to the data known by that object.
Various methods are explained in further slides.
9

10. geocode() method
geocode() method is used to geolocate a query of given input address.
The output of the given program is:
(27.6877024, 85.3345680822887)
from geopy import Nominatim
geolocator = Nominatim(user_agent="OSM")
location = geolocator.geocode("Liverpool International College")
print((location.latitude, location.longitude))
10

11. geocode() method
geocode(query, exactly_one=True, timeout=None)
Parameters:
◦ query(String)= the address or query you wish to geocode.
◦ exactly_one(bool)= Return one result or a list of results, if available.
◦ Timeout(int)– Time, in seconds, to wait for the geocoding service to respond
11

12. reverse() method
Reverse(query, exactly_one=True,timeout=None,distance=None,wkid=4326)
Parameters:
◦ query(geopy.point.Point, list or tupel of (latitude,longitude))=The coordinates for which you
wish to obtain the closest human-readable addresses.
◦ exactly_one(bool)= Return one result,or a list?
◦ timeout (int) – Time, in seconds, to wait for the geocoding service to respond
◦ distance (int) – Distance from the query location, in meters, within which to search
◦ wkid (string) – WKID to use for both input and output coordinates.
12

13. reverse() method
reverse() method is used to find the corresponding to a set of coordinates.
The output of the given program is:
Kathmandu University, KU road, Kuttal, 28 Kilo, Dhulikhel, काभ्रेपलाञ्चोक,
बागमती अञ्चल, मध्यमाञ्चल विकास क्षेत्र, 09771, नेपाल
from geopy import *
geolocator = Nominatim(user_agent=“OSM")
location = geolocator.reverse((27.61866315,85.538226277388))
print(location.address)
13

14. geocode and reverse return three types of values:
None: when no value is found
Location as geopy.location.Location object when argument is true
A list of geopy.location.Location object when exactly one is false
When response is not received in allotted timeout, exception is received
(geopy.exc.GeocoderTimedOut)
14

15. Unit Conversion
There is provision of unit conversion on geopy in Geopy.units
Different units can be used for angle and distance conversion such as:
◦ Angle: Degrees, minutes, seconds and radians
◦ Distance: Mile, kilometer, feet, meter, nautical
15

16. Functions available for angle unit conversion are:
1. arcminutes(degrees=0, radians=0, arcseconds=0)
converts one of the input parameter into minutes
2. arcseconds(degrees=0, radians=0, arcminutes=0)
converts one of the input parameter into seconds
3. degrees(radians=0, arcminutes=0, arcseconds=0)
converts one of the input parameter into degrees.
4. radians(degrees=0, arcminutes=0, arcseconds=0)
converts one of the input parameter into radians.
There can be one or more arguments in each functions.
16
from geopy.units import *
print(degrees(radians= 3.14))
Output: 179.9087476710785

17. Functions available for distance conversion are:
1. feet( kilometres=0, meters=0, miles=0, nautical=0)
converts one of the input parameters into feet
2. kilometres(meters=0, miles=0, feet=0, nautical=0)
converts one of the input parameters into kilometres
3. meters( kilometres=0, miles=0, feet=0, nautical=0)
converts one of the input parameters into meters
4. miles( kilometres=0, meters=0, feet=0, nautical=0)
converts one of the input parameters into miles
5. nautical( kilometres=0, meters=0, miles=0, feet=0)
converts one of the input parameters into nautical
17
from geopy.units import *
print(feet(kilometers=90))
Output: 295275.59055118106

18. Distance Computation
calculates distance between two points by:
Geodesic distance
shortest distance on the surface of an ellipsoidal model of the earth
Great circle distance
uses a spherical model of the earth, using the mean earth radius as defined by the
International Union of Geodesy and Geophysics
18

19. geodesic() method
geodesic() method is used to calculate the distance between two co-ordinates
with a default of the geodesic distance available as the function
geopy.distance.distance.
from geopy import *
from geopy import Nominatim
from geopy.distance import *
geolocator = Nominatim(user_agent="OSM")
location1 = geolocator.geocode("Kathmandu")
location2 = geolocator.geocode("Pokhara")
ktm = (location1.latitude,location1.longitude)
pkh= (location2.latitude,location2.longitude)
d=str(geodesic(ktm,pkh).kilometers)
print("Distance between Kathmandu and Pokhara is :"+d+"km"
19

20. geodesic() method
The output of the given program is:
Distance between Kathmandu and Pokhara is :142.0431085720416km
20

21. great_circle()
Calculates distance from the method of great circle.
The output is: Distance between Kathmandu and Pokhara is
:141.8939645114832km
21
from geopy import *
from geopy import Nominatim
from geopy.distance import great_circle
geolocator = Nominatim(user_agent="OSM")
location1 = geolocator.geocode("Kathmandu")
location2 = geolocator.geocode("Pokhara")
ktm = (location1.latitude,location1.longitude)
pkh= (location2.latitude,location2.longitude)
d=str(great_circle(ktm,pkh).kilometers)
print("Distance between Kathmandu and Pokhara is :"+d+"km")

22. Different ellipsoids are available for calculating distance between two
location but the default ellipsoid is WGS-84
The sets of ellipsoids available is:
model major (km) minor (km) flattening
ELLIPSOIDS = {'WGS-84': (6378.137, 6356.7523142, 1 /298.257223563),
'GRS-80': (6378.137, 6356.7523141, 1 / 298.257222101),
'Airy (1830)': (6377.563396, 6356.256909, 1 / 299.3249646),
'Intl 1924': (6378.388, 6356.911946, 1 / 297.0),
'Clarke (1880)': (6378.249145, 6356.51486955, 1 / 293.465),
'GRS-67': (6378.1600, 6356.774719, 1 / 298.25),
}
22

23. We can also can change the ellipsoid model used by the geodesic formulas like:
Here, ellipsoid GRS-80 is used.
23
from geopy import *
from geopy.distance import geodesic
print(distance.geodesic(27,35,ellipsoid='GRS-80').miles)
Output:551.1330125824877
from geopy import *
from geopy.distance import geodesic
print(geodesic(27,35 ,ellipsoid=(6377.0, 6356.0, 1 / 297.05)).miles)
Output:551.0256807403239

24. EXCEPTIONS
geopy.exc.geopyError: all exceptions are inherited from GeopyError
geopy.exc.GeocoderNotFound exception: when the string passed in geocode()
is not recognized.
geopy.exc.GeocoderQueryError: when geopy detected input that cause
request to fail or if the geocoding service responded that request was bad.
geopy.exc.GeocoderTimedOut: when no service has been received in the
given timeout argument
geopy.exc.GeopyError: when no geocoder could be found.
Etc.
24

25. Uses of the module
Can be used during natural disaster assessment to locate the affected areas.
Can be used in extracting the filtered raw information from web services.
Can be used with various module.
for example: geopy with pandas is used to create a database in rows and columns.
25

26. References
URL: https://geopy.readthedocs.io/en/stable/
o Accessed date: 18th December,2018
URL:https://pypi.org/project/geopy/
o Accessed date: 18th December, 2018
URL:https://www.youtube.com/watch?v=5z4v4qX2_7c
o Accessed date: 19th December,2018
26

27. 27