How to use logical indexing to return parts of an array that matches the elements of another array?

Hi all,

I have two signals 'a" and 'b' (attached) collected at the same time (see figure below). I have identified certain events in signal ''a'' (attached "a_events_frames' and 'a_events_values'/ plotted over signal a in the figure). Now I want:

• Return and save parts of the signal B that corresponds to parts in A between events 1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8

Can you help please?

Answer 1

[KSSV]

Read about findpeaks. It will give you the indices and values of peaks; using the indices you can get yopur required values.

[Tomaszzz]

Thank you. Indices and values of peaks of 'A' is what I already have. Since the signals were collected at the same time, I want to apply these over signal B that correspond to these events. Rather than applying find peaks again for signal B which will require diffrent set of rules.

[KSSV]

If both the signals are recorded at the time stamps, use the same indices of A. If you don't want to use findpeaks for B.

[Tomaszzz]

Yes, they are recorded at the same time stamps. What you said is where I fail so this:

signal b(a_indices)

returns values of b at correct indices but not indices of b itself. Also, even if I get indices of b how to return elements of b between indices 1 and 2, 2and 3 and so on?

[KSSV]

b(a_indices) 

The above line will give you values in b at the indices a_indices. It will not give you indices from b. Already you have indices a_indices.

If you know the indices of peaks 1,2,3,etc. You can get the values betweent he peaks using:

a(id1:id2)  % id1 is index of peak1, id2 is index of peak 2 
a(id2:id3)  % id2 is index of peak2, id3 is index of peak 3