Could you please tell me why the last part for the descending order isn´t working? Thank you!

c=[4,5,3;10,30,50;200,900,40]';
c=sortrows(c,1);
d=sortrows(c,3,'descend');

[Stephen23]

"Could you please tell me why the last part for the descending order isn´t working?"

What does "isn't working" mean? Are you getting an output that you do not expect? (if so what do you expect?) Or is MATLAB throwing an error? (if so, what is the complete error message, and what MATLAB version are you using?)

Answer 1

[Stephan]

Hi,

I will try to guess what you mean:

You want it sorted in ascending order after the first column and descending at the same time after the third column.

If we extend your numerical example a little, then it goes like this:

c=[4,5,3,4,3;10,30,50,40,10;200,900,40,1000,50]

gives

c =

             4          10         200
             5          30         900
             3          50          40
             4          40        1000
             3          10          50

now:

d = sortrows(c,[1 3],{'ascend', 'descend'})

gives:

d =

             3          10          50
             3          50          40
             4          40        1000
             4          10         200
             5          30         900

You wanted to do so?

Regardless of whether I have guessed right or wrong, what could be your problem:

Nevertheless, Stephen is absolutely right - The question is very unclear and gives no concrete statement of what your problem is. It is helpful for the volunteers here, if the questions are put as concrete as possible, error messages are attached and if necessary attachments are provided.

Best regards

Stephan

[Tobias Schädel]

Hi Stephan,

thank you for the quick answer. I am sorry for the unclear question. But you guess right.

After this:

d = sortrows(c,[1 3],{'ascend', 'descend'})

I get this error:

Error using sortrows Too many input arguments.

Error in test (line 2) d = sortrows(c,[1 3],{'ascend', 'descend'})

I am using Matlab R2015a, academic use.

Thank you.

[Stephen23]

@Tobias Schädel: check the help of your MATLAB (not the online help): does it allow a cell array as the third argument?

[Stephan]

Hi Tobias,

after answering you i saw that Steven Cobeldick gave the better answer - try like he suggested:

d = sortrows(c,[1 -3])

This should give you the result you expect and is much shorter. See Stevens answer below and accept it if you are happy now.

Best regards

Stephan

[Tobias Schädel]

Thanks to all. The commends 'ascend' and 'descend' aren´t working in my version. But this is working.

    d = sortrows(c,[1 -3])

[Stephan]

Hi Tobias,

fine. In order to help people with similar problems finding helpful answers, please accept S helpful answers.

Best regards

Stephan

Answer 2

[Stephen23]

Perhaps one of these does what you want:

>> c = [4,5,3;10,30,50;200,900,40]'
c =
     4    10   200
     5    30   900
     3    50    40
>> sortrows(c,[1,-3])
ans =
     3    50    40
     4    10   200
     5    30   900
>> sortrows(c,[-3,1])
ans =
     5    30   900
     4    10   200
     3    50    40