CODEWITHSUNDEEP
matlab
TimeIsNear
TimeIsNear

Reputation: 755

matlab - Sort cells array according mode

How can I sort a matrix using a specific column, with changing direction? I've tried this, but don't work.

data:
    A1  5  P19
    A2  7  P45
    A3  8  P7

[Y,I] = sort(data(:,3), 'descend');
B = data(Y,3);

I need to get:

In Ascending
    A3  8  P7
    A1  5  P19
    A2  7  P45

In descending:
        A2  7  P45
        A1  5  P19
        A3  8  P7

Thanks for your help.

Upvotes: 1

Views: 155

Answers (2)

Luis Mendo
Luis Mendo

Reputation: 112689

To sort in alphabetical order (not what you want) according to column 3:

[Y,I] = sort(data(:,3)); %// I gives the indices of sorted rows 
B_asc = data(I,:); %// ascending
B_des = data(I(end:-1:1),:); %// descending

To sort in numerical order (which seems to be what you want) according to column 3 without the "P":

aux = strvcat(data(:,3)); %// put column 3 into matrix form, with trailing spaces
[Y,I] = sort(str2num((aux(:,2:end)))); %// convert to number and sort
B_asc = data(I,:); %// ascending
B_des = data(I(end:-1:1),:); %// descending

Upvotes: 3

Robert Seifert
Robert Seifert

Reputation: 25232

Assuming your data is a cell matrix:

A = {'A1'  5  'P19'; 'A2'  7  'P45'; 'A3'  8  'P7'};
temp = char(A(:,3));
temp = str2num(temp(:,2:end));  %get rid of the P

[~,idx1] = sort(temp,'ascend')
A(idx1,:)

will give you:

'A3'    [8]    'P7' 
'A1'    [5]    'P19'
'A2'    [7]    'P45'

and

[~,idx2] = sort(temp,'descend')
A(idx2,:)

will give you:

'A2'    [7]    'P45'
'A1'    [5]    'P19'
'A3'    [8]    'P7'

If your data could be changed to:

A = {'A1'  5  'P19'; 'A2'  7  'P45'; 'A3'  8  'P07'};

it would make everything easier, as everybody initially thought here:

B = sortrows(A,3);
C = flipud(B);

B = 

    'A3'    [8]    'P07'
    'A1'    [5]    'P19'
    'A2'    [7]    'P45'


C = 

    'A2'    [7]    'P45'
    'A1'    [5]    'P19'
    'A3'    [8]    'P07'

Upvotes: 3

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