Display data ONLY inside closed polygons

Hi there!

I have a quiite unique problem.I have a data of elevation in particular area, and able to display it using pcolor (the xy coordinates and data were given).Also, I have a shape file consist of this a particular city border, and able to display its border lines it using shaperead and mapshow (the x and y coordinates also given as a form of struct).

My question is, how can I display the pcolor data mentioned above ONLY inside the closed region of this polygons (in other words, display the data only inside the city, and assign the rest as NaN).

Thank you!

Answer 1

[jonas]

Super simple if you have X,Y,Z with Z being elevation as well as a closed polygon defined by xp and yp

%some sample data
[X,Y] = meshgrid(0:100,0:100);
Z = X+Y;

%polygon
xp = [20,50,50,20];
yp = [20,20,50,50];

%find pts inside and remove
in = inpolygon(X(:),Y(:),xp,yp);
Z(~in) = NaN;

%display
surf(X,Y,Z)

[Abdul Kadir Alhamid]

So the function to do this is inpolygon? Great! thanks for your help.