How to keep unique rows

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

Answer 1

[Paolo]

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'     }

[Mekala balaji]

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

[Paolo]

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.