How to insert missing data in?

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Jaffatron 2015-4-14

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https://ww2.mathworks.cn/matlabcentral/answers/203419-how-to-insert-missing-data-in

评论： Amin Rajabi 2020-12-17

I carried out an experiment and automatically got readings.

However the apparatus was supposed to take a reading every 0.1 seconds, and sometimes it was offline but the apparatus kept counting but didn't print these in the. For example:

It would go 98.5, 98.6, 99.0. I'm looking a way to put blank rows in where there is missing data, such as it'll read 98.5, 98.6, 98.7, 98.8, 98.9, 99.0. And to give values of Nan for these. Doing it individually isn't an option, as there is a vast amount of data (864,00 for a day).

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回答（2 个）

Adam 2015-4-14

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https://ww2.mathworks.cn/matlabcentral/answers/203419-how-to-insert-missing-data-in#answer_175195

编辑：Adam 2015-4-14

在 MATLAB Online 中打开

times = [98.5 98.6 99.0];
readings = [123 345 567];
expectedTimes = 98.5:0.1:99.0;
newReadings = NaN( size( expectedTimes ) );
newReadings( ismember( expectedTimes, times ) ) = readings;

is one method. Obviously extendible to larger data read in rather than my small hard-coded example.

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Adam 2015-4-17

ismember does act a little suspiciously sometimes, I'm not sure what its underlying algorithm is.

I had to remove its usage from something I was doing with custom classes recently. For ages it was working fine to check if a given object was a member of an array of objects, but then in some circumstances it began to return 0 claiming the object was not a member. An isequal (...) call on the object and the member of the array that I knew matched it returned true, however so I ended up just changing to use a different implementation.

Amin Rajabi 2020-12-17

Thank you very much, I was looking for a quick way for adding missing records to a vector (a vector that is shorter than the original expected one). It works perfectly.

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Jaffatron 2015-4-17