Increase execution speed of saving using matfile

Question

Stefan 2019-2-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/447252-increase-execution-speed-of-saving-using-matfile

回答： Jan 2019-2-27

I want to continously save data (in appdesigner if that is relevant), therefore I create a matfile object on startup and then append data using a timer:

"Main"

app.SavingObject = matfile(app.FileName,'Writable',true);

And in a timer:

app.SavingObject.Data(app.sizeMyVar(1)+1:app.sizeMyVar(1)+size(NewPoints,1),1:app.sizeMyVar(2)) = NewPoints;

This will append my Data in the correct way.

What bothers me, if profiling this, you will see, that 40% of the time is spent internally using "whos". Sure this can be adjusted by the amount of how much data is written per call (I write ~60k Values per call), but it somehow feels like a waste of time and the amount of data per call is kind of fixed in my setup.

Is there a way to increase the wrtiting speed?

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Answer 1

Jan 2019-2-27

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/447252-increase-execution-speed-of-saving-using-matfile#answer_362991

A MAT file can contain a set of variables and store the data in compressed form. Appending new data to an existing variable is expected to be slow. It would be much more efficient to use a binary file and export the data to the MAT file at the end of the process at once.