Question

Suppose there is a 4-dimensional array A of size klmn. I want to obtain an array B of size KLmn by interpolating A along the first two dimensions. More precisely, what I want to do conceptually is in the code below. But how to make it more efficient avoiding the loops? Thank you.

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Answer 1

这就是我认为您打算做的事情（将您的代码更改为在原始矩阵的范围内进行插值）：

% Initialization
k=10;l=10;m=10;n=10;
K=100; L=100;
B=NaN(K,L,m,n);

% Just for the sake of example:
vec_k=1:k; 
vec_l=1:l; 
vec_K=linspace(1,k,K); 
vec_L=linspace(1,l,L); 
A=rand(k,l,m,n); 

% Interpolation
for ind_m=1:m
   for ind_n=1:n
      A_aux=squeeze(A(:,:,ind_m,ind_n));
      B(:,:,ind_m,ind_n)=interp2(vec_k',vec_l,A_aux,vec_K',vec_L,'spline');
   end 
end

使用interpn

也可以完成

[in{1:4}]=ndgrid(vec_k,vec_l,1:m,1:n);
[out{1:4}]=ndgrid(vec_K,vec_L,1:m,1:n);
X=interpn(in{:},A,out{:},'spline');

Interpolating a multidimensional object along two dimensions in Matlab

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