How can I use the returned sort index from the sort() function on a multidimensional array?

Question

David Berfanger 2023-11-30

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054579-how-can-i-use-the-returned-sort-index-from-the-sort-function-on-a-multidimensional-array

编辑： Matt J 2023-11-30

According to the documentation:

[B,I] = sort(___) also returns a collection of index vectors for any of the previous syntaxes. I is the same size as A and describes the arrangement of the elements of A into B along the sorted dimension. For example, if A is a vector, then B = A(I).

However, if A is not a vector, then B ~= A(I) since the sort index is returned as a collection of index vectors oriented along the same dimension that sort operates on rather than a linear index.

Is there a function to convert such a sort index into a linear index array, say f(I), such that B = A(f(I)), where f(x) would be similar in theory to sub2index() with the other dimensions inferred from the size of the sort index?

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Answer 1

Matt J 2023-11-30

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054579-how-can-i-use-the-returned-sort-index-from-the-sort-function-on-a-multidimensional-array#answer_1363404

编辑：Matt J 2023-11-30

在 MATLAB Online 中打开

sortlidx.m

The easier way would be to use the attached modification of sort() which will simply return the output indices as lienar indices.

Example:

A=randi(100,5),
A = 5×5
    24    33    22    38    11
    56     1    48    44     2
    90    79    76    97    94
    32    18    91    67    73
    46    66    72    47    71
[B1,I]=sortlidx(A,2);
B1,
B1 = 5×5
    11    22    24    33    38
     1     2    44    48    56
    76    79    90    94    97
    18    32    67    73    91
    46    47    66    71    72
B2=A(I)
B2 = 5×5
    11    22    24    33    38
     1     2    44    48    56
    76    79    90    94    97
    18    32    67    73    91
    46    47    66    71    72