How to create my own landmask?

Hi, I would like to create my own landmask for my model. Until now, my script looks like this:

index_land=isnan(land); %if 1 then land
[x, y] = meshgrid(lon, lat);
land=x.*index_land'; %if 0 then ocean
land(land==0)=nan;%if 0 (=ocean) then nan
h=pcolor(x, y, land);%plot landmask

But my questions now consists in: How can I change my script to be able to use it like a function? I would like to use this pcolor-landmask-plot in several plots. Thank you for your suggestions!

[Image Analyst]

What is land to begin with? Some kind of data with nans in it? What do you want land to be after you turn it into a mask? A logical image with true and false where there is or isn't land (which is the most typical and sensible way to have a mask)?

[anne d.]

In the beginning, land is a matrix where the land is described by nans and the ocean has data values. To plot my ocean data a bit more clearly I would like to create and plot a grey coloured land mask.

Answer 1

[anne d.]

No suggestions/ideas?