mlosch/interp_llc/xyexpand.m

function [To]=xyexpand(Tin,niter)
% Tout=xyexpand(Tin,3);
% 
% This function takes 2D input and replaces any NaN
% neighbouring any real numbers with the average of
% those numbers. This procedure is repeated niter
% times. Note that the ocean/land volume ratio expands
% rapidly with each iteration.
%
% In short, this is a gap-filler and extrapolator of
% rudimentary order applied to horizontal slices.
%
% Created  08/15/99 by adcroft@mit.edu
% Modified 11/11/99 by adcroft@mit.edu
% Maintained by adcroft@mit.edu, abiastoch@ucsd.edu

[nx,ny]=size(Tin);
ip=[2:nx 1];
im=[nx 1:nx-1];
jp=[2:ny ny];
jm=[1 1:ny-1];

T=Tin;
for iter=1:niter,

msk=ones(nx,ny);
L=isnan(T);
msk( L )=0;

To=T;
To( L )=0;

cnt=msk(im,:)+msk(ip,:)+msk(:,jm)+msk(:,jp);
cnt( find(cnt==0) )=1;
Tbr=(To(im,:)+To(ip,:)+To(:,jm)+To(:,jp))./cnt;

To( L )=Tbr( L );

To( find(To==0) )=NaN;

T=To;
end
1	function [To]=xyexpand(Tin,niter)
2	% Tout=xyexpand(Tin,3);
3	%
4	% This function takes 2D input and replaces any NaN
5	% neighbouring any real numbers with the average of
6	% those numbers. This procedure is repeated niter
7	% times. Note that the ocean/land volume ratio expands
8	% rapidly with each iteration.
9	%
10	% In short, this is a gap-filler and extrapolator of
11	% rudimentary order applied to horizontal slices.
12	%
13	% Created 08/15/99 by adcroft@mit.edu
14	% Modified 11/11/99 by adcroft@mit.edu
15	% Maintained by adcroft@mit.edu, abiastoch@ucsd.edu
16
17	[nx,ny]=size(Tin);
18	ip=[2:nx 1];
19	im=[nx 1:nx-1];
20	jp=[2:ny ny];
21	jm=[1 1:ny-1];
22
23	T=Tin;
24	for iter=1:niter,
25
26	msk=ones(nx,ny);
27	L=isnan(T);
28	msk( L )=0;
29
30	To=T;
31	To( L )=0;
32
33	cnt=msk(im,:)+msk(ip,:)+msk(:,jm)+msk(:,jp);
34	cnt( find(cnt==0) )=1;
35	Tbr=(To(im,:)+To(ip,:)+To(:,jm)+To(:,jp))./cnt;
36
37	To( L )=Tbr( L );
38
39	To( find(To==0) )=NaN;
40
41	T=To;
42	end