2D Interpolation & Extrapolation with non linear Sample grid points and nan
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Laurent Davenne
el 23 de Jun. de 2022
Comentada: Voss
el 24 de Jun. de 2022
Hi,
I have this 2D map wich I would like to interpolate to make square but also extrapolate.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1043460/image.png)
interp2 does seem to work with nan inputs as it just returns same nan as output.
V=[1.029 1.000 1.060 1.048 nan nan nan
1.049 1.014 1.038 1.092 1.075 nan nan
nan 1.039 1.079 1.036 1.029 1.003 nan
nan nan 1.042 1.072 1.000 0.998 1.028
nan nan nan 1.038 1.024 1.076 1.022
nan nan nan nan 1.082 0.997 1.011];
X=[8 10 15 25 35 45 52];
Y=[5 10 16.25 22.5 28.75 35];
Xq=ones(numel(Y),numel(X)).*X;
Yq=ones(numel(Y),numel(X)).*Y';
Z=interp2(X,Y,V,Xq,Yq)
I tried some inpaint functions from the community but none of them seems to be made to work with non linear sample grid points (0 2 7 17...).
I am open to suggestions
Thanks in Advance
Laurent
4 comentarios
Respuesta aceptada
Voss
el 24 de Jun. de 2022
Editada: Voss
el 24 de Jun. de 2022
V = [ ...
1.029 1.000 1.060 1.048 nan nan nan
1.049 1.014 1.038 1.092 1.075 nan nan
nan 1.039 1.079 1.036 1.029 1.003 nan
nan nan 1.042 1.072 1.000 0.998 1.028
nan nan nan 1.038 1.024 1.076 1.022
nan nan nan nan 1.082 0.997 1.011]
X = [8 10 15 25 35 45 52]; % using the X and Y from your code rather than
Y = [5 10 16.25 22.5 28.75 35]; % from your image, which are 5 less
% make a scatteredInterpolant of the points where V is non-NaN
[XX,YY] = meshgrid(X,Y);
idx = ~isnan(V(:));
I = scatteredInterpolant(XX(idx),YY(idx),V(idx));
% interpolate/extrapolate to all points
Z = reshape(I(XX,YY),numel(Y),[])
% visualization
x_lim = [min(X) max(X)];
y_lim = [min(Y) max(Y)];
z_lim = [min(Z(:)) max(Z(:))];
temp = {V Z};
names = {'V' 'Z'};
for ii = [1 2]
subplot(2,1,ii)
surface(XX,YY,temp{ii},'FaceColor','interp')
set(gca(),'YDir','reverse')
view(2)
xlim(x_lim);
ylim(y_lim);
xlabel('X');
ylabel('Y');
colorbar();
caxis(z_lim);
title(names{ii});
end
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