If I plot a group of points like the one below, how do I differentiate and extract say the points on the bottom boundary? What about 3 dimensions?

enter image description here

  • $\begingroup$ Interesting question! Would you please provide the code for the shown example? $\endgroup$ – Henrik Schumacher Mar 13 '18 at 8:14
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    $\begingroup$ I guess it should be easy to adapt upper envelope of data $\endgroup$ – Kuba Mar 13 '18 at 8:22
  • $\begingroup$ @HenrikSchumacher My code is most complicated and generate a large number of points, I don't know how to encapsulate them:< $\endgroup$ – 2ub Mar 13 '18 at 8:24
  • $\begingroup$ @Kuba The example you provided seems to not extract the boundary points but only to fit a proper function as boundary? $\endgroup$ – 2ub Mar 13 '18 at 8:26
  • $\begingroup$ @updraft not really, while answers aim in providing a smooth result, most of them has an intermediate step of extracting the envelope. btw, search around 'envelope points' and similar keywords, there are few related topics. $\endgroup$ – Kuba Mar 13 '18 at 8:29