MATLAB function for interpolating 2d matrix

interp_nan2d.m

function mat_interp = interp_nan2d( mat, kernel_size )
%
% MATLAB function for interpolating 2d matrix
% 
% Interpolating nan in 2D matrix 
% Hio-Been Han, hiobeen.han@kaist.ac.kr
% 2021-03-09.
% 
shape = size(mat);
if nargin < 2,kernel_size = ceil( mean(shape)/50 );end
mat_interp = mat;
[nan_x, nan_y] = find( isnan(mat ));
for idx1 = 1:length(nan_x)
    for idx2 = 1:length(nan_y)
        xIdx = nan_x(idx1)-kernel_size:nan_x(idx1)+kernel_size;
        yIdx = nan_y(idx2)-kernel_size:nan_y(idx2)+kernel_size;
        xIdx(find(xIdx<1))=[];yIdx(find(yIdx<1))=[];
        xIdx(find(xIdx>shape(1)))=[]; yIdx(find(yIdx>shape(2)))=[];
        box = mat(xIdx, yIdx);
        mat_interp(xIdx, yIdx) = nanmean(box(:));
    end
end

end