Finding 4 closest points

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Sanskar Patel 2021-4-23

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/811030-finding-4-closest-points

回答： Rik 2021-4-23

Hi,

So I am trying to use bilinear interpolation to extrapolate data for certain values of a 3-dimensional array. But, the issue is that the bilinear interpolation requires an input of the 4 closest numbers by distance in order for the equations to be solved. Does anyone have an idea of how I can obtain these 4 values. I am going to put some context below for better understanding.

62 0 63 0

0 0 0 0

63 0 61 0

0 0 0 0

I am going to refer to the coortinates of the elements in the form of (row,column).

So for example, consider this array above. For context, I need a way to find the 4 closest non-zero points to (1,2). If I solved this manually, the points would be (1,1),(1,3),(3,1),(3,3).

This is only a small part of a very large array that I have given for context. If anyone can help me with the coding, it would be appreciated.

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Jonas 2021-4-23

编辑：Jonas 2021-4-23

what aboit using find() with two output arguments which gives you the x and y index of the nonzero elements. after then you can calculate on the base of this indices the distance to the locations you are interested in.

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Answer 1

Rik 2021-4-23

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https://ww2.mathworks.cn/matlabcentral/answers/811030-finding-4-closest-points#answer_682785

You can design something yourself, but you could also see if fillmissing solves your problem. The documentation suggests it should work for 3D arrays as well.