How to find points inside a country border

Hi everyone, I have a 2 dimension matrix containing lat, lon of multiple points. I would like to ask whether there is any way in Matlab to define which points are inside the border of a specified country. Any suggestion would be greatly appreciated!

Answer 1

[Akira Agata]

How abou the following?

(In this script, I have used shape file provided in http://thematicmapping.org/downloads/world_borders.php)

% Load shape file of country border
S = shaperead('TM_WORLD_BORDERS_SIMPL-0.3.shp');
S = struct2table(S);

% Target lat and lon (e.g Tokyo)
lat = 35.7;
lon = 139.7;

% Find which country contains (lat,lon) 
idx = cellfun(@(X,Y) inpolygon(lon,lat,X,Y),S.X, S.Y);

% Show the result
disp(S.NAME(idx))

>> disp(S.NAME(idx))

'Japan'

[Thao Linh Tran]

Great! I got it, many thanks for your help.

[FRANCO CERVERA]

Hello,

I am trying to select coordinates points from a specified countries and your script would help me very much but i have problems by running it. Could you please help me to understand what to do with this error message from the script above ?

thank you !

Error using tabular/dotParenReference

Unrecognized table variable name 'NAME'.

Error in test_shapefile (line 12)

disp(S.NAME(idx))

[Adam]

Thank you @Akira Agata! Your code above works beautifly. However, when I tried the coordinates for a coastal city, the display returned no results. Upon closer inspection, I found the polygons contained in your shapefile were too coarse. I updated to the World Bank Official Boundaries shapefile (download), updated the table header from "NAME" to "FORMAL_EN" and everything is working well.

Answer 2

[KSSV]

Read about inpolygon

[Thao Linh Tran]

Thank you for your suggestion!

Answer 3

[FRANCO CERVERA]

Hello,

I am trying to select coordinates points from a specified countries and your script would help me very much but i have problems by running it. Could you please help me to understand what to do with this error message from the script above ?

thank you !

Error using tabular/dotParenReference

Unrecognized table variable name 'NAME'.

Error in test_shapefile (line 12)

disp(S.NAME(idx))

[KSSV]

The error says, in the table S, there is no variable/ column with name NAME.