Grouping elements in a matrix

Question

Anjan Dadgupta 2023-1-20

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1897770-grouping-elements-in-a-matrix

回答： Dyuman Joshi 2023-1-20

I have a

matrix, lets call it M. The elements of M have values between -2 to +2. For example, M is a row matrix,

and it is given by

M = [2 1.3 1.4 1.1 -1 -0.9 -0.5 0 0.5 0.9 1.1 0.9 1.6 0.8 0.2 1.1....]

I would like to sort the elemnts according to:

.

i.e., in the above example, the grouping should look like this: {2 1.3 1.4 1.1 -1}, { -0.9 -0.5 0 .5 0.9},{1.1}, { 0.9 }, {1.6},{0.8 0.2}, {1.1}..

Similarly, I would like to do this kind of sorting at each row for a matrix M(i,j).

Can anyone please help me how to do it in MATLAB?

Thanks!

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Matt J 2023-1-20

编辑：Matt J 2023-1-20

I for one do not understand the grouping criterion. Are you just grouping monotonically increasing/decreasing runs of numbers together? How should the final result be stored if there are a different number of groups in each row of M? And what do you plan to do with the groups once you've isolated them?

Fangjun Jiang 2023-1-20

在 MATLAB Online 中打开

M = [2  1.3  1.4  1.1  -1  -0.9  -0.5  0  0.5  0.9  1.1  0.9  1.6  0.8  0.2  1.1];
index=and(M>-1, M<1)
index = 1×16 logical array
   0   0   0   0   0   1   1   1   1   1   0   1   0   1   1   0

For one row of data, I think the logic for grouping is to check the change of value in "index" above

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Answer 1

Dyuman Joshi 2023-1-20

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1897770-grouping-elements-in-a-matrix#answer_1153015

在 MATLAB Online 中打开

M = [2  1.3  1.4  1.1  -1  -0.9  -0.5  0  0.5  0.9  1.1  0.9  1.6  0.8  0.2  1.1];
index=and(M>-1, M<1);
idx=unique([1 find(diff(index)~=0)+1 numel(M)+1]);
out=mat2cell(M,1,diff(idx))
out = 1×7 cell array
    {[2 1.3000 1.4000 1.1000 -1]}    {[-0.9000 -0.5000 0 0.5000 0.9000]}    {[1.1000]}    {[0.9000]}    {[1.6000]}    {[0.8000 0.2000]}    {[1.1000]}