Separate numbers present within a cell on multiple rows

Hi. I retrieved the first N numbers (largest to smallest) from the second column of the 'CountArray' array.

Now I wanted to determine the corresponding value on the first column of the 'CountArray' array by creating a column vector with these values.

I tried this way but, for example on row 22 and row 23 of cell 'matrix', there are two (equal) values because in 'values_rec' there is the same number (24).

CountArray = importdata("CountArray.mat");

N = 30;
values_rec = maxk(CountArray(:,2),N);
    
matrix = {};
    
for K = 1:height(values_rec)

    [row,col] = find(CountArray(:,2) == values_rec(K));
    
    value = CountArray(row);
    
    matrix = [matrix;{value}];
    
end

matrix = cell2mat(matrix);

So I have to transform 'matrix' in this way:

Answer 1

[Voss]

Take advantage of the second output of maxk, which is a vector of indices of the maxk values.

CountArray = importdata("CountArray.mat");

N = 30;
[values_rec,idx] = maxk(CountArray(:,2),N);
matrix = CountArray(idx,1);

disp(matrix)

    71
    70
    69
    72
    68
    73
    74
    67
    75
    76
    77
    66
    78
    79
    80
    81
    65
    82
    83
    64
    84
    85
    90
    94
    86
    93
    89
    95
   134
    87

https://www.mathworks.com/help/matlab/ref/maxk.html#d124e959021

Answer 2

[dpb]

whos -file CountArray.mat

  Name             Size            Bytes  Class     Attributes

  CountArray      86x2              1376  double              

load CountArray.mat
N = 30;
[values_rec,ix] = maxk(CountArray(:,2),N);
matrix=CountArray(ix,1);
matrix(19:30)

ans = 12×1

83 64 84 85 90 94 86 93 89 95

See maxk doc; return the optional output of the location as well and you've already got the answer.