Unrecognized table row name

Question

LeoAiE 2021-9-6

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链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1447944-unrecognized-table-row-name

评论： LeoAiE 2021-9-7

采纳的回答： Walter Roberson

Test.xlsx

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Hello everyone,

I have a table and I want to subscript using a column contain a string array. Basically, the column is repeated countries names and I used unique to get unique values. Then I wanted to get all the available information from the table about those countries. I understand I will lose some data from other columns, but this is not a concern at this time. I get an error message saying “unrecognized row name”

Any other methods can achieve the results? here is my code and my data

Data = readtable('Test.xlsx');
Data.country = string(Data.country);
Data(unique(Data.country),:)

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Answer 1

Walter Roberson 2021-9-7

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1447944-unrecognized-table-row-name#answer_782109

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In order to index by a string or categorical in the first index of a table, the values have to have been set as the RowNames property.

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/730924/Test.xlsx';
Data = readtable(filename);
Data.Properties.RowNames = string(Data.country);
Duplicate table row name: 'Andorra'.
Data(unique(Data.country),:)

You can see from this that every row name must be unique.

The indexing done with the first index of a table is not equivalent to a SELECT operator that would select all matches. Instead, the RowName that is set must be unique, must identify exactly one row in the table.

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Walter Roberson 2021-9-7

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If you want to get at the first match for each country:

filename = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/730924/Test.xlsx';
Data = readtable(filename);
Data.country = string(Data.country);
[~, ia] = unique(Data.country);
Data(ia,:)
ans = 19×4 table
latloncountryRandomCode_______________________________________________

     33.939        67.71    "Afghanistan"                41    
     41.153       20.168    "Albania"                    53    
    -14.271      -170.13    "American Samoa"             59    
     42.546       1.6016    "Andorra"                     1    
    -11.203       17.874    "Angola"                     95    
     18.221      -63.069    "Anguilla"                   54    
    -75.251    -0.071389    "Antarctica"                 24    
     17.061      -61.796    "Antigua and Barbuda"        79    
    -38.416      -63.617    "Argentina"                  83    
     40.069       45.038    "Armenia"                    53    
     12.521      -69.968    "Aruba"                      99    
    -25.274       133.78    "Australia"                  58    
     47.516        14.55    "Austria"                    64    
     40.143       47.577    "Azerbaijan"                 83    
     23.685       90.356    "Bangladesh"                 95    
     13.194      -59.543    "Barbados"                   46    

LeoAiE 2021-9-7

@Walter Roberson Thank you so much I really appreciate your help. I always enjoy reading detailed explanations when you answer my questions and have a full understanding of where I missed up and how to fix it! You are awesome man. Keep up the great work.

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