Find indexes in time-series signal

Question

JCanal 2018-11-12

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https://ww2.mathworks.cn/matlabcentral/answers/429481-find-indexes-in-time-series-signal

评论： KSSV 2018-11-13

Hi,

Im searching for x indexes of a given y value in a time-series signal.

What function should I use since the exact y value Im looking for sometimes do not exist?

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Answer 1

KSSV 2018-11-13

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编辑：KSSV 2018-11-13

在 MATLAB Online 中打开

YOu may have a look on this example code:

% signal
x = linspace(0,2*pi)' ; 
y = sin(x) ;
% Get the x index for yi
yi =  randsample(y,1) ;
% Do interpolation 
xi = interp1(y,x,yi) ;
% GEt the index 
idx = knnsearch([x y],[xi yi]) ;
value = [xi yi]
iwant = [x(idx) y(idx)]

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KSSV 2018-11-13

在 MATLAB Online 中打开

YOu may also use this approach:

% signal
x = linspace(0,2*pi)' ; 
y = sin(x) ;
% Get the x index for yi
yi =  randsample(y,1) ;
% Check for abolute zero 
idx = abs(y-yi)<=10^-3 ;
yi
iwant = [x(idx) y(idx)]