Sorting a matrix by one column

Question

José Pereira 2017-12-7

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https://ww2.mathworks.cn/matlabcentral/answers/371647-sorting-a-matrix-by-one-column

评论： José Pereira 2017-12-7

So i have this "matrix". First column is names, second colomn is passwords. I want to display this data alphabetically by name. I don´t know how to do this.So here is the original matrix,

     {'john'}    {'jojo'}
     {'victor'}    {'vivi'}
     {'andre'}    {'dredre'}

and here is the result i want to display:

    {'andre'}    {'dredre'}
     {'john'}    {'jojo'}
     {'victor'}    {'vivi'}

Thanks!

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Answer 1

KL 2017-12-7

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编辑：KL 2017-12-7

在 MATLAB Online 中打开

That's not a matrix. If you meant to store them in cell arrays,

C = {'john', 'jojo';'victor', 'vivi';'andre', 'dredre'};

It would look like

 C =
  6×1 cell array
    'john'      'jojo'  
    'victor'    'vivi'  
    'andre'     'dredre'

Now use just sortrows

https://www.mathworks.com/help/matlab/ref/sortrows.html

 C = sortrows(C,1)
 3×2 cell array
    'andre'     'dredre'
    'john'      'jojo'  
    'victor'    'vivi'

Neverthless better idea to store such data is to use tables,

 names = {'John';'victor';'andre';};
 passwords= {'jojo';'vivi';'dredre'};
 T = table(passwords,'RowNames',names)

and it looks like,

 T =
  3×1 table
              passwords
              _________
    John      'jojo'   
    victor    'vivi'   
    andre     'dredre'

now, again sortrows,

 sortrows(T)
   3×1 table
              passwords
              _________
    andre     'dredre' 
    John      'jojo'   
    victor    'vivi'

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KL 2017-12-7

在 MATLAB Online 中打开

If you are still opting to use cell array, then simply use sort and only for first column. Extract the sorted indices from the result and use it sort the original cell array.

C = {'john', 'jojo';'victor', 'vivi';'andre', 'dredre'}
[~,indx] = sort(C(:,1));
sortedC = C(indx,:)
sortedC =
3×2 cell array
    'andre'     'dredre'
    'john'      'jojo'  
    'victor'    'vivi'