I reaally shouldn't be giving you the answer, since you've shown absolutely no effort to create this plot yourself. But I'm bored at work waiting for some simulations to finish, so it's your lucky day.
First of all, I'm assuming that you already have a shapefile holding the India boundary, and that you have a raster grid of x (lon), y (lat), and z coordinates. Also, I'm assuming that your data grid isn't already trimmed to the India borders.
So, the first quick-and-dirty way to do this is to simply mask the data points outside the border:
file = 'TM_WORLD_BORDERS-0.3.shp';
S = shaperead(file, 'usegeocoords', true, 'selector', ...
{@(x) strcmp(x,'India'), 'NAME'});
x = linspace(min(S.Lon), max(S.Lon), 100);
y = linspace(min(S.Lat), max(S.Lat), 100);
[x,y] = meshgrid(x,y);
z = rand(100);
isin = inpolygon(x,y,S.Lon,S.Lat);
z2 = z;
z2(~isin) = NaN;
figure('color','w');
worldmap('India');
pcolorm(y,x,z2);
plotm(S.Lat, S.Lon, 'k');
You'll notice that things get a little jagged around the edges, though. You can get a cleaner map by plotting all the data, then overlaying it with a polygon that masks out all but your region of interest. (Or in this case, polygons, since neither geoshow nor patchm tend to play well with polygons with holes):
lnlim = [65 100];
ltlim = [5 40];
lt = linspace(ltlim(1), ltlim(2), 3);
ln = linspace(lnlim(1), lnlim(2), 3);
for ii = 1:2
ltbox{ii} = lt([1 2 2 1 1]'+(ii-1));
lnbox{ii} = ln([1 1 2 2 1]'+(ii-1));
end
[lnmask, ltmask] = deal(cell(2));
for ii = 1:2
for jj = 1:2
[lnmask{ii,jj}, ltmask{ii,jj}] = polybool('-', ...
lnbox{ii}, ltbox{jj}, S.Lon, S.Lat);
end
end
ltboxall = ltlim([1 2 2 1 1]);
lnboxall = lnlim([1 1 2 2 1]);
[lnmaskall, ltmaskall] = polybool('-', lnboxall, ltboxall, S.Lon, S.Lat);
figure('color','w');
worldmap('India');
pcolorm(y,x,z);
for ii = 1:4
patchm(ltmask{ii}, lnmask{ii}, 'w', 'edgecolor', 'none');
end
plotm(ltmaskall, lnmaskall, 'k');
Best Answer