Sorting operation on a string matrix

Question

klb 2021-5-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/821740-sorting-operation-on-a-string-matrix

编辑： dpb 2021-5-6

采纳的回答： Stephen23

在 MATLAB Online 中打开

Hi everyone,

My code for sorting string. Question in comment:

s = ["1 9:53.3";
     "3 9:23.5";
     "5 2:16.2";
     "2 2:45.6";
     "4 12:01.2"]
s = split(s," ",2);
stab = array2table(s);
stab.s1 = double(stab.s1);
stab = sortrows(stab,"s1","ascend");
stab.s1 = string(stab.s1);
stab = table2array(stab)
% Question : How do I get the sorted matrix as a 5X1 matrix now?

Required sorted output matrix :

s =[  "1 9:53.334"
      "2 2:45.623"
      "3 9:23.545"
      "4 12:01.213"
      "5  2:16.245"]

Suggestions, if any, for better/more effficient ways to this string data are welcome.

Thanks for your time in advance.

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klb 2021-5-5

编辑：klb 2021-5-5

Stephen, you got there before I did ! When it encounters 1,2,3,..11,12..20,21... it sorts data as 1,10,11...2,20,21...

dpb 2021-5-5

编辑：dpb 2021-5-5

". it sorts data as 1,10,11...2,20,21... "

Of course it does; that was the point of asking why you're so stuck on trying to treat numeric data as character...note again that Stephen's solution has to convert to numeric first (as he also points to a better storage design) so why not just do that from the git-go instead of making it more difficult than needs be?

There is a lexical sort (and why TMW hasn't builtin one is anybody's guess) on FEX altho I don't have the link right now at hand...

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Answer 1

Stephen23 2021-5-5

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/821740-sorting-operation-on-a-string-matrix#answer_692195

编辑：Stephen23 2021-5-5

在 MATLAB Online 中打开

s = ["1 9:53.3";
     "3 9:23.5";
     "5 2:16.2";
     "2 2:45.6";
     "4 12:01.2"];
[~,X] = sort(str2double(extractBefore(s,' ')));
out = s(X,:)
out = 5×1 string array
    "1 9:53.3"
    "2 2:45.6"
    "3 9:23.5"
    "4 12:01.2"
    "5 2:16.2"

Note that much better data design would store numeric data as a numeric type.

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dpb 2021-5-6

编辑：dpb 2021-5-6

在 MATLAB Online 中打开

>> s=split(s);
>> data=table(str2double(s(:,1)), ...
              duration(s(:,2),'InputFormat','mm:ss.S','Format','mm:ss.S'), ...
              'VariableNames',{'N','T'})
data =
  5×2 table
    N       T   
    _    _______
    1    09:53.3
    3    09:23.5
    5    02:16.2
    2    02:45.6
    4    12:01.2
>> sortrows(data,'N')
ans =
  5×2 table
    N       T   
    _    _______
    1    09:53.3
    2    02:45.6
    3    09:23.5
    4    12:01.2
    5    02:16.2
>>

Or, alternatively, if were interested in the time/duration

>> sortrows(data,'T')
ans =
  5×2 table
    N       T   
    _    _______
    5    02:16.2
    2    02:45.6
    3    09:23.5
    1    09:53.3
    4    12:01.2
>> 

Nothing could be easier; NB: the table is a wonderfully powerful container for mixed data types; much more flexible than just a cell array and far more convienent than holding in either separate arrays or to try to machinate on text when it really isn't text...

If you were to have begun with a text file instead of a string array, you surely would have used readtable or similar tool to import as the type of data in the file; the message is to treat the source text the same way despite its origin.

klb 2021-5-6

Thanks for the time and feedback @dbp Follwing the answer to this question I already went ahead with remainder of the data processing; it includes steps same as first option you share. Well, after sorting. Your solutions are noted. Please post it as an answer poper - It will have better visibilty to the community and I can upvote it.

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