clustering nearest 5 elements of a data

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sreelekshmi ms 2020-2-15

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/505594-clustering-nearest-5-elements-of-a-data

评论： sreelekshmi ms 2020-2-23

采纳的回答： Turlough Hughes

Pimaxl.xlsx

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I have 36 points I need to find the nearest 5 elements of each point and cluster it in a group. Then there is a total of 36 clusters will get. The points are in the 'core' and I need to find the nearest elements from the 'data'. How can I do that? Please help me.

clc;
clear;
data=xlsread('Pimaxl.xlsx');
Si=size(data);
asc=sort(data);
num = numel(data);
diff=unique(asc);
core1=maxk(diff,12);
core2=mink(diff,12);
n = numel(diff(:));
midpoint = ceil(n/2);
core3 = diff(midpoint-5:midpoint+6);
cor=[core1 core2];
core=[cor core3];

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Rik 2020-2-15

core is 12x3, while data is 768x9. What is your definition of point and what is your definition of distance? Is every single element a point and is the distance the absolute difference?

Turlough Hughes 2020-2-15

Have a look at the answer I provided here

You could do the same as that but just replace min with mink. Also as pointed out in the comments a sqrt is not needed.

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采纳的回答

Turlough Hughes 2020-2-15

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https://ww2.mathworks.cn/matlabcentral/answers/505594-clustering-nearest-5-elements-of-a-data#answer_415703

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You could do the following which is to find the 5 minimum absolute differences for each element in core.

[~,idx] = mink(abs(data(:)-core(:).'),5,1);
clusters = data(idx)

Here, the input array to mink is 6912 by 36 where each row corresponds to an element in data and each column corresponds to an element in core and contains every possible absolute difference. The mink function returns an index that you can then sub directly back into data to get your clusters. Clusters is 5 by 36 with each column corresponding to the 36 values in core.