How to count the number of consecutive repetitions of an array?

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giovanni negro 2018-4-12

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https://ww2.mathworks.cn/matlabcentral/answers/394454-how-to-count-the-number-of-consecutive-repetitions-of-an-array

评论： Walter Roberson 2021-1-15

Hi everybody,

I have a double array or a logical one made like this above: A=[0 1 1 1 0 0 1 0 1 1 0 0 0 1 0 1 1 1]; And I would like to count the number of consecutive repetitions of values 1, getting as output an array like this: B=[3 1 2 1 3], where 3=3 times 1; 1=1 time 1; ecc.. Please, can someone help me with this issue?

Thanks a lot!

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采纳的回答

James Tursa 2018-4-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/394454-how-to-count-the-number-of-consecutive-repetitions-of-an-array#answer_314772

在 MATLAB Online 中打开

E.g.,

[r,s] = runlength(A,numel(A));
result = r(logical(s));

You can find runlength on the FEX:

https://www.mathworks.com/matlabcentral/fileexchange/241-runlength-m

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Walter Roberson 2021-1-15

Your A vector contains values between 1 and 235, not the 0 and 1 of the original Question. What is it that you want to compute on your A?

Walter Roberson 2021-1-15

在 MATLAB Online 中打开

Your A vector has no runs at all. Every value that occurs, occurs in isolation, with there never being two of the same value in a row. You cannot do any useful run-length encoding on it -- not unless you are able to go into pairs of values instead of single values.

load a.mat
results = {};
for targ = unique(A).'
   a = A.' == targ;
   starts = strfind([0 a], [0 1]);
   if isempty(starts); continue; end
   stops = strfind([a 0], [1 0]);
   results{end+1, 1} = [targ, stops - starts + 1];
end
celldisp(results)