# Find set of all adjacent points that are close to each other

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Paul Hoffrichter on 5 Jun 2020
Edited: Paul Hoffrichter on 6 Jun 2020
I would like to find in Y[n] a set of adjacent points that are close to each other, but I don't get all the desired points. For example.
Y = [ 1.1 1.12 9.2 8.3 8.295 8.292 4.1 4.12 4.19];
dY_idx = find(abs(diff(Y)) < 0.022);
This code results in:
1.1000 8.3000 8.2950 4.1000
But I would like the result to be:
1.1000 1.1200 8.3000 8.2950 8.2920 4.1000 4.12
How can I get the desired result? (Note: I probably could also do a Y = fliplr(Y) followed by a second round and then combine results to get all the unique points, but that would be two sets of operations on a large vector. Hoping for a faster solution.)

Tommy on 5 Jun 2020
logidx = abs(diff(Y)) < 0.022;
Y_adj_close = Y([logidx 0] | [0 logidx]);
1.1000 1.1200 8.3000 8.2950 8.2920 4.1000 4.1200
Paul Hoffrichter on 6 Jun 2020
Edited: Paul Hoffrichter on 6 Jun 2020
My new question deals with my need to keep dimension of x and y the same. I forgot to mention that in this question. I used your answer here to work out an answer that works. Just wondering whether it can be modified to perform better.
Just using plot in the question to ensure dimensions match, and provide a quick sanity check.