Find negative in every n rows

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David du Preez 2017-5-12

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https://ww2.mathworks.cn/matlabcentral/answers/339987-find-negative-in-every-n-rows

评论： Andrei Bobrov 2017-5-15

I have a 2184 x 14 matrix. In column 1 is the datenum value and in column 14 the values that I want to consider. The other columns contain some other data.

I want to consider the first 24rows if any of the values in column 14 are negative. I want to delete the first 24rows and then repeat this for the following 24rows.

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Answer 1

Andrei Bobrov 2017-5-12

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https://ww2.mathworks.cn/matlabcentral/answers/339987-find-negative-in-every-n-rows#answer_266754

编辑：Andrei Bobrov 2017-5-15

在 MATLAB Online 中打开

One way

% A - your data [2184 x 14]
ii = ceil((1:size(A,1))'/24);
jj = accumarray(ii,A(:,14),[],@(x)all(x >= 0)); % EDIT
out = A(jj(ii),:);

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David du Preez 2017-5-15

编辑：David du Preez 2017-5-15

matlab.mat

That does not work. It does not find any negative neither removes them. attached in the matrix in question

Andrei Bobrov 2017-5-15

I'm fixed my answer.

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Answer 2

Jan 2017-5-15

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/339987-find-negative-in-every-n-rows#answer_267083

编辑：Jan 2017-5-15

在 MATLAB Online 中打开

Data   = rand(2184, 14) - 0.1;  % Test data
D      = reshape(Data, 24, [], 14);
Match  = any(D(:, :, 14) < 0, 1);
Result = reshape(D(:, Match, :)), [], 14);