How to replace zeros in a vector with random segments of the same vector?

Question

Bence Laczó 2022-3-24

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https://ww2.mathworks.cn/matlabcentral/answers/1679404-how-to-replace-zeros-in-a-vector-with-random-segments-of-the-same-vector

编辑： Bence Laczó 2022-3-25

I have a vector with 240000 data points. There are several, 72 elements long segments of zero values in that vector. Now I would like to replace these segments of zeros with random 72 elements long segments from the remaining non zero part of the vector.

Can you help me how can I do it?

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Answer 1

Image Analyst 2022-3-24

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https://ww2.mathworks.cn/matlabcentral/answers/1679404-how-to-replace-zeros-in-a-vector-with-random-segments-of-the-same-vector#answer_925919

在 MATLAB Online 中打开

Try this:

% First we need to create the data since the original poster forgot to attach it for us.
% Make random vector with values in the 1-9 range.
v = randi(9, 1, 24000);
% Make 20 stretches of 72 zeros.
startingIndexes = sort(randi(length(v), 1, 20))
for k = 1 : length(startingIndexes)
    v(startingIndexes(k) : startingIndexes(k) + 71) = 0;
end
% Now we have our vector and we can begin.
%---------------------------------------------------------------------------------
% First find out what the non-zero values are
% that we can use to plug the regions of zeros.
% tic; % Start timer
availableToUse = unique(nonzeros(v));
% Now plug the zeros with numbers randomly chosen from availableToUse
for k = 1 : length(v)
    if v(k) == 0
        % It's zero so replace it with a random number chosen from availableToUse.
        randomIndex = randi(length(availableToUse), 1, 1);
        v(k) = availableToUse(randomIndex);
    end
end
% toc % End timer

Time to execute is 0.002 seconds (2 milliseconds).

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Bence Laczó 2022-3-25

编辑：Bence Laczó 2022-3-25

rawdata.mat

Thank you very much for the help! I'm really appreciate your kindness!

I think I was not precise when I described my problem. I have to replace the 72 elements long segments of zeros, with random, but existing 72 elements long segments of the remaining data. So not with random single numbers, but with 72 consecutive numbers.

Now I have attached the original data.

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Answer 2

Arif Hoq 2022-3-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1679404-how-to-replace-zeros-in-a-vector-with-random-segments-of-the-same-vector#answer_925739

在 MATLAB Online 中打开

try this:

A=[1 2 3 0 0 0  4 5 0 0 0 0 0 0 0 0 8 9]';  % any matrix
B=A(A==0);   % extract the number of 0
rdnumber=randi([10 20],size(A,2),numel(B));  % generating random number 
A(A==0)=rdnumber  % replace with random number
A = 18×1
     1
     2
     3
    14
    14
    18
     4
     5
    19
    17