我想在给定的数据向量中查找峰值和低谷,具有以下定义。
“峰值”是局部最大值,比前一个谷值高至少x%,“谷值”是局部最小值,比前一个峰值低至少x%。这里的x被称为截止。在我写的论文中,截止值被称为数据的标准差。
我想写一个功能,让我找到一个高峰和一个低谷。我写的功能就是这个。我将从主要数据中调用它。
function [vectpeak,vecttrough]=peaktrough(cutoff,x,lastobs,t)
% This function gives you two outputs: a vector of ones and zeros that locate PEAKS and
% a vector of ones and zeros that locate TROUGHS.
% To be able to get a vector of peaks and troughs, we have to give
% four inputs.
% CUTOFF: This is what Chang and Osler [1999] use to identify if a data
% point is a peak or a trough. A PEAK is defined as "a local maximum that is
% x percent higher than the preceding trough." (Chang and Osler, 1999)
% and a TROUGH is defined as "a local minimum that is x percent lower
% than the preceding peak." This is a scalar.
% VECTOR: This is the vector of data that will be used for the purposes of
% the identification.
% LASTOBS: This is the last observation of the data.
% t: This specifies the time.
% Pre-allocations.
vectpeak=zeros(lastobs,1); % This is the vector of peaks.
vecttrough=zeros(lastobs,1); % This is the vector of troughs.
% Computing for the troughid's and peakid's.
temptroughid=troughid(cutoff,x,lastobs,t);
temppeakid=peakid(cutoff,x,lastobs,t);
% Determining whether a function is a peak or a trough.
while t<lastobs
t=t+1;
if x(t)>=temptroughid(t);
vecttrough(t)=1;
vectpeak(t)=0;
maximum=x(t);
elseif x(t)<=temppeakid(t);
vecttrough(t)=0;
vectpeak(t)=1;
minimum=x(t);
else
vecttrough(t)=0;
vectpeak(t)=0;
end
end
function findtrough=troughid(cutoff,y,lastobs,t)
% This function computes for the TROUGHID which will be used in
% determining whether we have a trough or a peak.
% Initializations.
findtrough=zeros(lastobs,1);
tempmin=zeros(lastobs,1);
minimum=y(1);
% This is how the function works.
while t<lastobs;
t=t+1;
if y(t)<minimum;
tempmin(t)=y(t);
minimum=y(t);
else tempmin(t)=minimum;
end
findtrough(t)=tempmin(t)*(1+cutoff);
end
end
function findpeak=peakid(cutoff,y,lastobs,t)
% This function computes for the PEAKID which will be used in
% determining whether we have a peak.
% Initializations.
findpeak=zeros(lastobs,1);
tempmax=zeros(lastobs,1);
maximum=y(1);
% This is how the function works.
while t<lastobs;
t=t+1;
if y(t)>maximum;
tempmax(t)=y(t);
maximum=y(t);
else tempmax(t)=maximum;
end
findpeak(t)=tempmax(t)*(1-cutoff);
end
end
end
我得到的问题是我得到了奇怪的结果。例如,我得到一个矢量,其中所有都是峰值,没有一个是低谷,这没有意义,因为如果我使用MATLAB的findpeaks
命令,我能够识别峰值和谷值,它们不是连续。
有没有办法我可以调整我的代码,或者如果没有,使用findpeaks或其算法根据我的定义找到峰值和低谷?
答案 0 :(得分:0)
实际上,您的代码实际上并未识别峰值或波谷。我认为你应该从findpeaks开始,以获得候选峰值和低谷的列表。然后,逐步执行此列表以测试每个是否满足条件。