problem in sorting an array with "sortrows" command

Question

Mahsa Rm 2021-12-18

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1613755-problem-in-sorting-an-array-with-sortrows-command

编辑： Stephen23 2021-12-18

I have two arrays, one is time and other is direction. I want to sort the directions by time by using the code below. the direction is sorted well but my time array is ruined. how can I fix this? (because I still need the time array)

code's result is shown in the image.

any help will be appreciated.

 timeorder=[3.4,7,1,8,5.1,9];
>> direction=['u','d','L','r','u','r'];
>> sorted = (sortrows([timeorder',direction'], 1))' ;
>> timord = sorted(1,:);
>> drc = sorted(2,:);

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Stephen23 2021-12-18

编辑：Stephen23 2021-12-18

在 MATLAB Online 中打开

Note that is MATLAB square brackets are a concatenation operator, so this

['u','d','L','r','u','r']

is just a complex way of writing this:

'udLrur'

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Answer 1

Dave B 2021-12-18

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https://ww2.mathworks.cn/matlabcentral/answers/1613755-problem-in-sorting-an-array-with-sortrows-command#answer_857865

编辑：Dave B 2021-12-18

在 MATLAB Online 中打开

A good way to sort one array using the order of another is with the second output argument of sort:

timeorder=[3.4,7,1,8,5.1,9];
direction=['u','d','L','r','u','r'];
[sortedtimeorder, sortind] = sort(timeorder)
sortedtimeorder = 1×6
    1.0000    3.4000    5.1000    7.0000    8.0000    9.0000
sortind = 1×6
     3     1     5     2     4     6
sorteddirection=direction(sortind)
sorteddirection = 'Luudrr'

However if you really wanted to use sortrows, you could always convert the values in timord back to numeric (MATLAB turned them into char for you when you combined the two vectors into a matrix):

timeorder=[3.4,7,1,8,5.1,9];
direction=['u','d','L','r','u','r'];
sorted = (sortrows([timeorder',direction'], 1))' ;
timord = sorted(1,:);
drc = sorted(2,:);
double(timord)
ans = 1×6
     1     3     5     7     8     9