如何找到數據集的拐點？

Question

我的代碼找到它們的拐點和位置，但有些點丟失。有什麼方法可以在MATLAB上找到正確的點嗎？

Answer 1

有一個解決方案here：

findinflections.m

% function [datapeaks datavalleys] = findinflections(plotswitch,datain) 
% This program finds peaks 
% Arguments: 
% ploswitch: 0 or 1 : disable or enable plots (for debugging) 
% datain: 1D variable 
% Dependencies: 
% 
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function [datapeaks datavalleys] = findinflections(plotswitch,datain) 
% datain = gconv; 
datad1=[diff(datain)]; 
mp = find(datad1>0); 
mn = find(datad1<=0); 

datapeaks = []; 
for pindex = 1:length(mp) 
    [maxvalue, maxindex] = max(datain(mp(pindex):mn(min(find(mn>mp(pindex)))))); 
    if ~isempty(maxindex) 
     datapeaks = cat(1,datapeaks, floor(mean(maxindex))+mp(pindex)-1); 
    end 
end 
datapeaks= unique(datapeaks); 

datavalleys = []; 
for pindex = 1:length(mn) 
    [minvalue, minindex] = min(datain(mn(pindex):mp(min(find(mp>mn(pindex)))))); 
    if ~isempty(minindex) 
     datavalleys = cat(1,datavalleys, floor(mean(minindex))+mn(pindex)-1); 
    end 
end 
datavalleys= unique(datavalleys); 

if (plotswitch) 
    plot(1:length(datain),datain,'k-',mp,datain(mp),'b.',mn,datain(mn),'r.',datapeaks,datain(datapeaks),'g.',datavalleys,datain(datavalleys),'c.'); 
end 

調用它（陣列一個是你分）：

[datapeaks, datavalleys]=findinflections(1,A); 

輸出：