selecting and extracting contiguous points as one event
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Commented: Stephen on 8 Jan 2019
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:
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.
Andrei Bobrov on 7 Jan 2019
let a - your data - vector.
out = sum(diff([0;a(:) > .13]) == 1);
More Answers (2)
tt = linspace(0,12,1001);
th = 0.4;
dd = [0,diff((s-th)>0)>0.5];
Image Analyst on 8 Jan 2019
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.
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