Software that tells you in what country is a given latitude/longitude

Question

In what country are the coordinates 41.44241, 21.31530 ?

A manual Google Maps search tells me it is in Macedonia.

Is there a program (or library) that would tell me this programmatically?

Requirements:

• If the coordinates are not in a country, it should say sea or something appropriate
• For contested areas like Kashmir, anything is fine, I am not picky
• Free
• Works on Linux
• If no library/program is available, a web API can be OK too but it must accept at least 50,000 requests daily

Answer 1

A simple method to match a set of latitudes and longitudes is to use QGIS and the Point Sampling Tool

1. Firstly, download and install QGIS
2. Download and install a spatial dataset of political boundary polygons (for example from naturalearthdata.com
3. Create a CSV containing your points and whatever other attributes you're interested in
4. Open QGIS and install the Point Sampling Tool plugin (instructions in the QGIS documentation)
5. Add the political boundaries to the project (instructions in the QGIS docs)
6. Add the CSV of the points of interest (instructions in the QGIS docs)
7. Use the Point Sampling Tool by clicking the icon in the toolbar
8. Select the attributes from both layers you want to keep in the new file, and create a new shapefile as output
9. Check the Add created layer to the TOC button to re-add the data to the map
10. Right click on the newly created layer in the Table of Contents and select Save Layer As
11. Select CSV and hit OK and you get a CSV with country points joined to the CSV

Answer 2

You're looking at Reverse Geocoding. If you're familiar with Python I'd recommend the geopy library which includes geocoders for a number of services including Yahoo, Google, and OpenStreetMap Nominatum.

Your issue will be the quantity of requests, which will depend on the license of the geocoding service that you use, so you'll have to examine those carefully. For 50 000 addresses per day you may end up having to pay for a service.

For example to use the Google geocoder assuming your points are a latitude/longitude coordinate pair:

from geopy.geocoders import GoogleV3

geolocator = GoogleV3()
location = geolocator.reverse((41.44241, 21.31530), exactly_one=True)
print(location.address)

If handling the larger volumes of data as @Nicolas Raoul suggests above you should really be downloading a dataset containing political boundaries (for example from naturalearthdata.com) and using a GIS system such as QGIS to intersect the data with your points.