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How can I average every other value in a 500 by 500 matrix

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Martin Jordan
Martin Jordan on 20 Aug 2019
Answered: Kritika Bansal on 23 Aug 2019
I have a matrix that is missing every other value and i am trying to interpolate it by taking the value of the number before and after and averaging the 2
this is what I have so far but it is not working any help is greaty appreciated!
[M,N] = size(B)
for i = 1:N
if N(i) == 0
H(i) = (N(i-1) + N(i+1))/2
else
H(i) = N(i)
end
end
for j = 1:M
if M(j) == 0
K(j) = (M(j-1) + M(j+1))/2
else
K(j) = M(j)
end
end
disp(B)
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Answers (1)

Kritika Bansal
Kritika Bansal on 23 Aug 2019
Hi,
There are few ways to do so in MATLAB. Some of them are listed below:
  1. Using interp2 function of MATLAB. As per my understanding of this function, if your data is non gridded, then there is a possibility that all the missing values are not interpolated. You can read more about this function here: https://www.mathworks.com/help/matlab/ref/interp2.html
  2. Using inpaint_nans function from the file exchange available at https://www.mathworks.com/matlabcentral/fileexchange/4551-inpaint_nans
If you want to do the averaging of the neighbours as you mentioned, you can take a look at the following code:
%x is the input matrix
[m,n] = size(x);
y=zeros(m,n);
for i=1:m
for j=1:n
if x(i,j)==0
if j==1
l=j;
else
l=j-1;
end
if j==n
r=j;
else
r=j+1;
end
val = (x(i,l)+x(i,r))/2;
y(i,j) = val;
else
y(i,j) = x(i,j);
end
end
end

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