find values from a matrix according to a criterion

Question

Richard 2012-9-17

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/48368-find-values-from-a-matrix-according-to-a-criterion

I have a time series of measurements as follows:

time = [733774,733774,733775,733775,733775,733776,733776];
data = [1,1.3,1,2.5,2.5,1,1.2];
Final = [time',data'];

I want to create a new variable that only contains the values that contain more than two measurements for individual days. So, from the example above, the result should be:

newData = [[733775;733775;733775],[1;2.5;2.5]];

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Answer 1

José-Luis 2012-9-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/48368-find-values-from-a-matrix-according-to-a-criterion#answer_59059

在 MATLAB Online 中打开

time = [733774,733774,733775,733775,733775,733776,733776];
data = [1,1.3,1,2.5,2.5,1,1.2];
unik_time = unique(time);
rep_time = arrayfun(@(x)  (sum(ismember(time,x)) > 2),unik_time);
idx = ismember(time,unik_time(rep_time));
your_time = time(idx);
your_vals = data(idx);

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Answer 2

Thomas 2012-9-17

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/48368-find-values-from-a-matrix-according-to-a-criterion#answer_59058

在 MATLAB Online 中打开

Something like this

time = [733774,733774,733775,733775,733775,733776,733776];
data = [1,1.3,1,2.5,2.5,1,1.2];
Final = [time',data'];
unique_days=unique(time);
for ii=1:length(unique_days)
count(ii)=sum(unique_days(ii)==time);
end
idx=find(count>2);
% If there is more than 1 day with 3 or more readings
for jj=1:length(idx)
idx_time(jj,:)=find(time==unique_days(idx(jj)));
newTime=time(idx_time(jj,:))
newData=data(idx_time(jj,:))
end