MATLAB: How to get index of each points in data

.

Let's say:
A= [ 111 111 111  22     %index 1
     999 999 999  11     %index 2
     555 555 555  44     %index 3
     222 222 222  33]    %index 4
If I want to reorder the rows in matrix A by sorting the elements of column 4 in ascending order, I will use this code:
sort_cell=arrayfun(@(c) sortrows(A,c),[4],'uniform',0);
% generate a cell by sorting matrix A in ascending of column 4
sort_A=sort_cell{:};
% convert cell "sort_cell_A"  to matrix
The result will as follows:
   sort_A= [ 999 999 999  11
             111 111 111  22
             222 222 222  33
             555 555 555  44 ]
My question is: How can I get back the index matrix from "sort_A" matrix? I hope the result will be:
index=[2
       1
       4
       3]

Best Answer

Simply use sortrows,
   >> [B,index] = sortrows(A,4)
  B =
     999   999   999    11
     111   111   111    22
     222   222   222    33
     555   555   555    44
index =
     2
     1
     4
     3
and below link has all you need:
https://de.mathworks.com/help/matlab/ref/sortrows.html
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