How to find n values before and after a maximum of an array

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Coryn Melissa LLamoza Carabali 2020-10-15

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评论： Ameer Hamza 2020-10-16

Hi, everybody, new to Matlab. I want to be able to locate the maximun peak which is known(always at 1) and to be able to extract the data right before and after this maximun peak(see example on figure). And this should be done even if the max-peak value changes along the x-as. Please help :(

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Mathieu NOE 2020-10-15

hello

use the "findpeaks" function to localise the peak signal position (index)

from this index value you can easily define a lower index = peak_index - 10 and an upper index = peak_index + 10

and generate an extract of your signal : signal_extract = signal(lower index : upper index)

good luck

Coryn Melissa LLamoza Carabali 2020-10-16

Hi, thank you for your answer. Is 'signal' a function? it doesn't seem to work :(

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Answer 1

Ameer Hamza 2020-10-15

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https://ww2.mathworks.cn/matlabcentral/answers/615103-how-to-find-n-values-before-and-after-a-maximum-of-an-array#answer_514998

编辑：Ameer Hamza 2020-10-15

在 MATLAB Online 中打开

Something like this will work

x; % array of x-values
y; % array of y-values
[max_y, max_idx] = max(y);
x_max = x(max_idx);
interval = 0.02; % length of interval before and after peak
idx = (x_max-interval < x) & (x < x_max+interval);
x_interval = x(idx);
y_interval = y(idx);