Finding local minima for a signal
100 次查看(过去 30 天)
显示 更早的评论
I have used the (findpeaks) function in Matlab in order to find the locations and the value of the peaks ( Local Maxima ) in the signal.
please, Is there any function to extract the local minimums of the following graph?
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/155563/image.jpeg)
0 个评论
采纳的回答
Walter Roberson
2016-8-8
If you have a routine that can find local maxima, then to find local minima, apply the local maxima routine to the negative of the data. Like
findpeaks(-X_Segments{nn},'MinPeakDistance', 20)
更多回答(3 个)
Image Analyst
2016-8-9
You're probably okay with your data, but beware of findpeaks() if your max or min spikes have flat tops or bottoms. It will give only the first index. In that case you want to use the imregionalmin() function from the Image Processing Toolbox. Just look at this example with a min that has a flat bottom:
data = [ 1 3 4 2 2 2 4 4 5 6] % Flat bottom with value of 2 from indexex 4-6
[peakValues, indexesOfPeaks] = findpeaks(-data)
peakValues = -peakValues
minIndexes = imregionalmin(data)
data =
1 3 4 2 2 2 4 4 5 6
peakValues =
-2
indexesOfPeaks =
4
peakValues =
2
minIndexes =
1 0 0 1 1 1 0 0 0 0
2 个评论
shima tavakoli
2018-2-13
my signal is asymmetric and its negative parts are different. how to deal with negative parts peaks then? cant negative the signal in this case!
1 个评论
Image Analyst
2018-2-13
Who knows? You forgot to read this and forgot to attach your signal and a screenshot of it, so there's not much I can say, other than to write custom code to deal with it.
另请参阅
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!