selecting and extracting contiguous points as one event
3 次查看(过去 30 天)
显示 更早的评论
I'm sure there is probably a drop-dead simple way to do this, but my brain is fried at the moment and I can't think of one. I'm trying to identify and count numbers of events that exceed a certain value in a time series. For example, a plot of the attached file yields:![Picture1.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/200334/Picture1.png)
![Picture1.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/200334/Picture1.png)
I'd like to be able to count the number of events that exceed the red line (y=0.13). Sometimes there is 1 point > 0.13 (e.g. the first event above at x=40) and that is easy to count as a single signal. But sometimes there are 2 or more contiguous points > 0.13 (e.g. the second event above, at x=56, 57), yet should be counted as just one "event", not as 2 events.
How can this be done? I've attached a file with the above signal.
采纳的回答
更多回答(2 个)
nanren888
2019-1-7
tt = linspace(0,12,1001);
s= sin(tt);
th = 0.4;
nnz(diff(s-th));
dd = [0,diff((s-th)>0)>0.5];
plot(tt,s,tt,dd);
grid('on');
nnz(dd)
ans =
2
![fig.png](https://www.mathworks.com/matlabcentral/answers/uploaded_files/200335/fig.png)
Image Analyst
2019-1-8
If you have the Image Processing Toolbox, the simplest way is to just use the function that was made to do exactly that: bwlabel
[~, numRegions] = bwlabel(signal > 0.13);
Can't get any easier than that.
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Time Series Events 的更多信息
产品
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!