MATLAB: Calculating an average in an n x m array that contain zeros

averagezeros

How can i calculate an average in an array where data in the columns are zero values and I don't want the zero to be considered when computig an average.

For example: A= [2 2 ; 2 4; 1 0] >>> mean(A) results in 1.667 2 >>>the answer I want is 1.667 3

Any assistance is much appreciated.

Best Answer

mn = sum(A)./sum(A~=0)

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MATLAB: Calculating average

Here is some code that might do the job. I am assuming that your image is truecolor, so the data have dimensions M x N x 3 for some M and N, and the colors are 24-bit, so the data type in R is uint8. If your images are different, you'll have to adjust the code:

n = length(dirlist);
R =  imread([pathname, dirlist(1).name]);
RR = zeros([size(Rav) n]);
% Put the images into an M x N x 3 x 60 array
for m2 = 2:n
  RR(:,:,:,m2) = imread([pathname, dirlist(m2).name]);
end
Rav = mean(RR,4); % average along the 4th dimension of the data
RR = bsxfun(@minus,RR,Rav); % subtract the average from each image

You can examine the kth image with

R = RR(:,:,:,k);
image(R)

MATLAB: Calculating Average Duration/Length in an Array

The histc function (with help from unique) is probably the easiest option:

W =  [3 3 3 1 1 1 1 2 1 1 2 3 3];
bins = unique(W);
k = histc(W,bins);
avg = k./2;

Best Answer

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MATLAB: Calculating average

MATLAB: Calculating Average Duration/Length in an Array

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