Store identical rows in specified column

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neamah al-naffakh 2022-3-12

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1670254-store-identical-rows-in-specified-column

评论： neamah al-naffakh 2022-3-17

采纳的回答： Scott MacKenzie

Example.csv

在 MATLAB Online 中打开

Hi ,

I have a table that has thousands of input, an example is attached

Date            ID         Name             Des
01/01/2021      2090260   'MIA'            'USA-MIAME'
01/01/2021      2090260   'MIA'            'USA-MIAME'             
01/01/2021      2094230   'ALOC'           'USA-NEW'
01/01/2021      2094230   'ALOC'           'USA-NEW' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA'  
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 

I want to check if each input in the second column (i.e., ID) IS EQUAL. If so, store it in a seperate array or table.

so the expected output would be

Date            ID         Name             Des
01/01/2021      2090260   'MIA'            'USA-MIAME'
01/01/2021      2090260   'MIA'            'USA-MIAME'             

Date            ID         Name             Des
01/01/2021      2094230   'ALOC'           'USA-NEW'
01/01/2021      2094230   'ALOC'           'USA-NEW' 

Date            ID         Name             Des
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA'  
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA' 
01/01/2021      2094700   'KATERINA'       'USA-FLORIDA'

I have written the following code but it doesnt work

clear;
% % data = Tbl.c;  
[~,~,data] = xlsread('Test.csv');
Selected_Data=(data(2:end,[1 2 3 4 6 9 10 18 ]));
% Remove NAN rows
Selected_Data(any(cellfun(@(x) any(isnan(x)),Selected_Data),2),:) = [];
Selected_Data1 = cell2table(Selected_Data);
Selected_Data2=sortrows(Selected_Data1,{'Selected_Data2'},{'ascend'});
Selected_Data2.Properties.VariableNames = {'TimeStamp' 'MMSI' 'LATITUDE' 'LONGITUDE' 'SPEED' 'IMO' 'NAME' 'DES'};
% this part doesnt work 
for i= 1:size(Selected_Data2,1) 
    for iter=1:size(Selected_Data2,1)    %Selected_Data2 is the table name
        if Selected_Data2(iter,2)=Selected_Data2(iter+1,2)    % check condition
             Segments=Selected_Data2(iter,:);                 % Store identical ID with all relevant data in a table or cell array
        end   
    end
    Group_Segment(i)=Segments;
end

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neamah al-naffakh 2022-3-12

Dear @Scott MacKenzie

Dataset is attached and the code is modified

thanks for your response

Scott MacKenzie 2022-3-12

OK, thanks. I just posted an answer.

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采纳的回答

Scott MacKenzie 2022-3-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1670254-store-identical-rows-in-specified-column#answer_916184

在 MATLAB Online 中打开

This seems to answer your question. There are 41 uniques IDs in the second column of your data set. The code below extracts the data/rows according the unique IDs and creates a new table. You can't create an array of tables in MATLAB, so it's not entirely clear what you want to do with each of the new tables. You could always use writetable within the loop to save each new table in a file.

T = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/924899/Example.csv');
u = unique(T.MMSI); % 2nd column, as per question
for i=1:length(u)
    Tnew = T(T.MMSI==u(i),:)     
    % do something with Tnew (perhaps write to file)
end