Percentage of time of a time series

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Jian Teng 2019-2-22

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https://ww2.mathworks.cn/matlabcentral/answers/446356-percentage-of-time-of-a-time-series

回答： Shunichi Kusano 2019-2-22

I have a series of RPM measurement and each measurement corresponse to a time. If I plot the time series of my RPM, it will looks like this:

The measurements are only recorded when the value are chaning, for example if 21:01 is 0 RPM, and 21:02 is also 0 RPM, the data on 21:02 will not be recorded.

My goal is figure out how to determine the percentage of the time, when the RPM is lower than 1, during the period (8PM to 5AM)?

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Answer 1

Shunichi Kusano 2019-2-22

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How about using diff function to your time vector data? The following is an example. The details need to be modified.

% time_vec: time stamp in order when RPM value changed. 
% val_vec: RPM values at time_vec
d_time = diff(time_vec);
total_duration = sum(d_time);
percentage = 100 * sum(d_time(val_vec < 1)) / total_duration;

if time_vec does not include the time of your targeted start-time and end-time, you need to insert them to time_vec as well as the corresponding values to val_vec.

hope this helps.