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

2 views (last 30 days)
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)
per isakson on 21 Aug 2019

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