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

Question

Paul Hoffrichter 2020-6-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/543065-find-set-of-all-adjacent-points-that-are-close-to-each-other

编辑： Paul Hoffrichter 2020-6-6

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);
Y_adj_close = Y(dY_idx)

This code results in:

Y_adj_close =
    1.1000    8.3000    8.2950    4.1000

But I would like the result to be:

Y_adj_close =
    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.)

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Answer 1

Tommy 2020-6-5

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/543065-find-set-of-all-adjacent-points-that-are-close-to-each-other#answer_447050

在 MATLAB Online 中打开

How about this?

logidx = abs(diff(Y)) < 0.022;
Y_adj_close = Y([logidx 0] | [0 logidx]);
Y_adj_close =
    1.1000    1.1200    8.3000    8.2950    8.2920    4.1000    4.1200

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Tommy 2020-6-5

You're very welcome, happy to help!

Paul Hoffrichter 2020-6-6

编辑：Paul Hoffrichter 2020-6-6

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.

https://www.mathworks.com/matlabcentral/answers/543197-plot-only-adjacent-points-that-are-close-to-each-other

Just using plot in the question to ensure dimensions match, and provide a quick sanity check.

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