CODEWITHSUNDEEP
matlab
Ahmet Kaymak
Ahmet Kaymak

Reputation: 19

How can I detect the minimum and maximum values every 50 rows

I'm trying to detect peak values in MATLAB. I'm trying to use the findpeaks function. The problem is that my data consists of 4200 rows and I just want to detect the minimum and maximum point in every 50 rows.
After I'll use this code for real time accelerometer data.

This is my code:

[peaks,peaklocations] = findpeaks( filteredX, 'minpeakdistance', 50 );
plot( x, filteredX, x( peaklocations ), peaks, 'or' )

Upvotes: 0

Views: 83

Answers (1)

GameOfThrows
GameOfThrows

Reputation: 4510

So you want to first reshape your vector into 50 sample rows and then compute the peaks for each row.

A = randn(4200,1);
B = reshape (A,[50,size(A,1)/50]); %//which gives B the structure of 50*84 Matrix
pks=zeros(50,size(A,1)/50); %//pre-define and set to zero/NaN for stability
pklocations = zeros(50,size(A,1)/50); %//pre-define and set to zero/NaN for stability
for i = 1: size(A,1)/50
[pks(1:size(findpeaks(B(:,i)),1),i),pklocations(1:size(findpeaks(B(:,i)),1),i)] = findpeaks(B(:,i)); %//this gives you your peak, you can alter the parameters of the findpeaks function.
end

This generates 2 matrices, pklocations and pks for each of your segments. The downside ofc is that since you do not know how many peaks you will get for each segment and your matrix must have the same length of each column, so I padded it with zero, you can pad it with NaN if you want.

EDIT, since the OP is looking for only 1 maximum and 1 minimum for each 50 samples, this can easily be satisfied by the min/max function in MATLAB.

 A = randn(4200,1);
 B = reshape (A,[50,size(A,1)/50]); %//which gives B the structure of 50*84 Matrix
 [pks,pklocations] = max(B);
 [trghs,trghlocations] = min(B);

I guess alternatively, you could do a max(pks), but it is simply making it complicated.

Upvotes: 1

Related Questions