Reducing nonzero values in vector and adding to subsequent zero values.

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I have a large vector of mostly zeros. I wish to divide the nonzero values by a value of N, and then add the divided value to the subsequent N-1 zero values. For example, if my vector is [....0 0 15 0 0 0 0 0 0 0....] and N=5, I want it to come out [....0 0 3 3 3 3 3 0 0 0....]. Thank-you for any tips!

Accepted Answer

Image Analyst
Image Analyst on 16 Feb 2016
Edited: Image Analyst on 16 Feb 2016
This works:
vector = [0 0 15 0 0 0 0 0 0 0 4 0 0 0 0 0 0 9 0]
N=5
nonZeroIndexes = find(vector ~= 0)
for k = 1 : length(nonZeroIndexes);
index1 = nonZeroIndexes(k)
index2 = min(index1 + N - 1, length(vector))
vector(index1 : index2) = vector(index1)/N;
end
% Display
vector
For max robustness, you'll have to define what you want to do in the case where two non-zero numbers are separated by less than N elements. It's not clear how you want to handle that.
  1 Comment
virkuz000
virkuz000 on 16 Feb 2016
Thanks! This does work in my program. And you're right, I will have to address when two nonzeros are less than N elements apart. Fortunately, I am helped by the fact that in the original vector, there are only 100 nonzero elements in a vector roughly 6000000x1 in size. So the likelihood of this problem occurring is very small.

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