Extreme points finding from set

2019 9 18
1 个回答
更新时间：2019 9 20
6 次查看（30 天）

0 个投票

d = xlsread('FaceFour_TRAIN.xlsx')
s = d(1:1,2:end);
fa = movstd(s,20,1);
secarray = movstd(fa,20,1) ;
secidx = find(secarray>.04);
f = secarray(secidx);
[maxvals, maxidx] = maxk(f,14);
sidx = secidx(maxidx);
x = 1:length(s);
key=plot(x, s, 'b-', sidx, s(sidx), 'go')
here the maximum points are extracted and plotted.I need to check and find only the extreme points from this,how can I do this.Please help me.

13 个评论
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Geoff Hayes
Geoff Hayes 2019-9-18
Silpa - please clarify what you mean by extreme. Are these the minimum and maximum points, or something else?
Silpa K
Silpa K 2019-9-18
The graph is like a wave.I mean the highest points that coming in the wave crest and wave trough.
Silpa K
Silpa K 2019-9-18
The graph likeScreenshot (30).png
Rik
Rik 2019-9-19
I suggested findpeaks in your duplicate post.
Silpa K
Silpa K 2019-9-19
Sir Iam new to matlab.If I used findpeaks only the peaks are extracting.How can I find both peak points and all the mininimum troughs points.And that points I need to mark in the original graph.Please help me.
Thank you.
Rik
Rik 2019-9-19
There are probably better ways, but if you do this
findpeak(-data)
you will find the local minima.
And once you have x and y, you should be able to plot those points.
Silpa K
Silpa K 2019-9-19
Iam getting 1×0 empty double row vector when I use this.
Rik
Rik 2019-9-19
Without your data and your code I can do nothing to help you. Have you read the documentation? I suspect it may return an empty vector is none of your peaks satisfy the requirements. Use the optional arguments to relax the requirements.
Silpa K
Silpa K 2019-9-20
d = xlsread('FaceFour_TRAIN.xlsx')
s = d(1:1,2:end );
fa = movstd(s,20 );
secarray = movstd(fa,20 ) ;
sec = secarray(secarray>.04 );
k=maxk(sec,14)
peak points of k
darova
darova 2019-9-20
Why those points are not extreme?
21Untitled.png
Silpa K
Silpa K 2019-9-20
Sir,It is only a sample graph.I need to find all the extreme points(Present in the crust and trough)
darova
darova 2019-9-20
HOw you define "extreme" point? Where is it?
Silpa K
Silpa K 2019-9-20
The maximum peak points present in the crust and trough.If I use findpeaks(d),then iam not getting the answer.
1×0 empty double row vector is the output coming.

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回答（1 个）

Steven Lord
Steven Lord 2019-9-19

0 个投票

I suspect some combination of islocalmin, islocalmax, and/or ischange will identify the points you've called out with + markers in your plot. All three of these functions were introduced as part of MATLAB in release R2017b.

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2019-9-18

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2019-9-20

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