How to find local peaks of plot? How to smooth data?

I'm looking to find the peak position of a data plot, to determine the distance between corresponding peaks. Also, I'd like to try smoothing the plot beforehand. Attached is an example of a plot I'm assessing.

Answer 1

[Star Strider]

The plot hasn’t appeared.

If you have the Signal Processing Toolbox, consider the findpeaks function. It should do essentially everything you need.

[Jason]

And if I don't have that toolbox? Sorry, I'm extremely new to MATLAB.

[Star Strider]

Without findpeaks you could write your own functions or search the File Exchange.

The way to find out if you have the Signal Processing Toolbox is to type in the MATLAB Command Window:

which findpeaks -all

If that comes up with one or more files in the core MATLAB directories (not user directories), you have the function and probably the complete toolbox.

The Signal Processing Toolbox can also help you smooth your data by filtering the high-frequency noise out of it. You mentioned smoothing as well, so I would investigate that.

Answer 2

[José-Luis]

Then look in the file exchange:

For example this function