How to keep unique rows

Question

Mekala balaji 2018-6-8

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https://ww2.mathworks.cn/matlabcentral/answers/404747-how-to-keep-unique-rows

评论： Paolo 2018-6-9

采纳的回答： Paolo

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Hi,

I have cell array matrix:

PreviousTable:
Time                  Name  Grp  Rank  Index  Attribute
2018-01-03 12:34:00   A     N    21    2      Good
2018-03-23 20:04:12   V     H    21    11     Good
2018-05-17 13:56:00   P     B    21    11     Good
CurrentTable:
Time                      Name  Grp  Rank  Index  Attribute    
  2018-05-17  13:56:00    P     B    21    11     Good
  2018-04-17  13:56:00    P     Q    21    11     Good
  2018-06-05  13:56:00    N     S    21    11     Good

Based on Name & grp columns, I want to retain the unique rows present in previousTable but not exist in currentTable,

For instance: 
2018-01-03 12:34:00   A     N    21    2      Good
2018-03-23 20:04:12   V     H    21    11     Good
are not exists in currentTable, and I want to retain from the previous Table:
My desired Output:
Time                      Name  Grp  Rank  Index  Attribute    
  2018-05-17  13:56:00    P     B    21    11     Good
  2018-04-17  13:56:00    P     Q    21    11     Good
  2018-06-05  13:56:00    N     S    21    11     Good
  2018-01-03 12:34:00     A     N    21    2      Good
  2018-03-23 20:04:12     V     H    21    11     Good

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Answer 1

Paolo 2018-6-8

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/404747-how-to-keep-unique-rows#answer_323849

编辑：Paolo 2018-6-8

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You can determine the common values between the two cell arrays with intersect. In the code below I combine columns Name and Grp both for both "tables" and compare them. The common values between the two are eliminated from PreviousTable, which is then appended to CurrentTable.

Your two cell array inputs:

PreviousTable:

 PreviousTable = {'Time','Name','Grp','Rank','Index','Attribute';
'2018-01-03 12:34:00' , 'A' , 'N' , 21 , 2 , 'Good';
'2018-03-23 20:04:12' , 'V' , 'H' , 21 , 11 ,'Good';
'2018-05-17 13:56:00' , 'P' , 'B' , 21 , 11 ,'Good'};

CurrentTable:

 CurrentTable = {'Time','Name','Grp','Rank','Index','Attribute';
'2018-05-17 13:56:00' , 'P' , 'B' , 21 , 11 , 'Good';
'2018-04-17 13:56:00' , 'P' , 'Q' , 21 , 11 , 'Good';
'2018-06-05 13:56:00' , 'N' , 'S' , 21 , 11 , 'Good'};
 %Find common values between arrays (C) and corresponding indexes (ia). 
 [C,ia,~] = 
 intersect(cell2mat(PreviousTable(2:end,2:3)),cell2mat(CurrentTable(2:end,2:3)),'rows','stable');
 %Delete redundant rows from first cell array.
 PreviousTable(ia+1,:) = [];
 %Append PreviousTable to CurrentTable.
 CurrentTable = [CurrentTable;PreviousTable(2:end,:)];

Output of CurrentTable:

    {'Time'            }    {'Name'}    {'Grp'}    {'Rank'}    {'Index'}    {'Attribute'}
    {'2018-05-17 13:5…'}    {'P'   }    {'B'  }    {[  21]}    {[   11]}    {'Good'     }
    {'2018-04-17 13:5…'}    {'P'   }    {'Q'  }    {[  21]}    {[   11]}    {'Good'     }
    {'2018-06-05 13:5…'}    {'N'   }    {'S'  }    {[  21]}    {[   11]}    {'Good'     }
    {'2018-01-03 12:3…'}    {'A'   }    {'N'  }    {[  21]}    {[    2]}    {'Good'     }
    {'2018-03-23 20:0…'}    {'V'   }    {'H'  }    {[  21]}    {[   11]}    {'Good'     }

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Mekala balaji 2018-6-9

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It works,
But Sir,
ia+1 is 4, and PreviousTable has only three rows, kindly explain the logic,

Paolo 2018-6-9

PreviousTable actually has four rows (1 header and 3 rows of data). The +1 is to exclude the first row of PreviousTable since it's a header and does not contain information you want to include in CurrentTable.

Please accept the question since it solved your problem.

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