Finding several local maximum values in a given range and corresponding indices

32 views (last 30 days)
If we have a dataset "y" which consists of a sum of 5 gaussian peaks as function of time t, there will be 5 local maximum values in the whole y values. Basically, I would like to obtain the y axis maximum values and their corresponding t axis values. For example peak 1, has a maximum value 5 and it corresponds to t value of 19.
untitled.jpg
One can individually find the maximum values by giving a range say
[a ,i]=max(y(1:20));% locating maxima in a given range of the first peak
value_1= t(i); % Corresponding value of time for index i1.
One can repeat this 5 times by specifying the ranges for all peaks. Is there a better way to achieve the same result as an output in a single vector, and the corresponding time for those maxima in another vector . Thanks.
  2 Comments
FW
FW on 27 Sep 2019
I have edited the question to clarify it. Basically, I would like to obtain the y axis maximum values and their corresponding t axis values. For example peak 1, has a maximum value 5 and it corresponds to t value of 19. I want to have all the 5 values of maximum and their corresponding time values?

Sign in to comment.

Accepted Answer

Star Strider
Star Strider on 27 Sep 2019
Use the Signal Processing Toolbox findpeaks function, or the islocalmax (R2017b and later) function.
  8 Comments
MW
MW on 28 Sep 2019
That sounds good, will try that. I hope Matlab includes peak area determination just like OriginPro where one can pan the area of interest and determine its area.
Star Strider
Star Strider on 28 Sep 2019
Thank you.
I hope Matlab includes peak area determination just like OriginPro where one can pan the area of interest and determine its area.
I doubt that’s an option, or if it is, I’ve not heard of it.
Fitting Gaussians is not difficult. See: Area under each peak for an illustration, including findpeaks calls. You can probably use that code with a few tweaks to use your own data. (I will help as necesary, since it’s my code. That code uses trapz, however it would probably not be very difficult to tweak it to use integral to calculate the areas, once the parameters of the Gaussians are known.)

Sign in to comment.

More Answers (1)

Image Analyst
Image Analyst on 28 Sep 2019
It looks like you already have an acceptable answer, but if you want code to fit some specified number of Gaussians to a signal, let me know - I have that, though not in a general purpose demo right now (I'd have to create that). Attach your signal if you need this.

Products

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!