Compare two tables with two column combinations

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Aletta Wilbrink
Aletta Wilbrink 2018-2-6
评论： Bradley Stiritz 2019-12-6
I have two tables, say:
t1 = table(categorical({'a';'b';'c';'c';'a';'b'}),categorical({'d';'e';'d';'f';'e';'d'}),[1;2;3;4;5;6],datetime({'2017-1-1 12:00 AM','2017-1-3 10:20 AM','2017-1-3 1:36 PM','2017-1-4 9:45 AM','2017-1-6 12:00 AM','2017-1-7 12:12 PM'})')
t2 = table(categorical({'a';'a';'c';'b';'c'}),categorical({'f';'d';'e';'f';'d'}),[5;4;3;2;1],datetime({'2017-1-1 12:00 AM','2017-1-3 6:20 AM','2017-1-3 1:36 PM','2017-1-4 9:45 AM','2017-1-6 12:10 AM'})')
t1 =
6×4 table
Var1 Var2 Var3 Var4
____ ____ ____ ____________________
a d 1 01-Jan-2017 00:00:00
b e 2 03-Jan-2017 10:20:00
c d 3 03-Jan-2017 13:36:00
c f 4 04-Jan-2017 09:45:00
a e 5 06-Jan-2017 00:00:00
b d 6 07-Jan-2017 12:12:00
t2 =
5×4 table
Var1 Var2 Var3 Var4
____ ____ ____ ____________________
a f 5 01-Jan-2017 00:00:00
a d 4 03-Jan-2017 06:20:00
c e 3 03-Jan-2017 13:36:00
b f 2 04-Jan-2017 09:45:00
c d 1 06-Jan-2017 00:10:00
Now I want the result or the rownumbers of every combination of the first two columns in t2 that are not in t1
How can I do this?
*Edited question with a little more complicated table

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采纳的回答

Peter Perkins
Peter Perkins 2018-2-6
tables have all the same "set membership" functions as numeric arrays:
>> t1 = table({'a';'b';'c';'c';'a';'b'},{'d';'e';'d';'f';'e';'d'});
>> t2 = table({'a';'a';'c';'b';'c'},{'f';'d';'e';'f';'d'});
>> [t3,i1] = setdiff(t1,t2)
t3 =
4×2 table
Var1 Var2
____ ____
'a' 'e'
'b' 'd'
'b' 'e'
'c' 'f'
i1 =
5
6
2
4
  3 个评论
显示 1更早的评论
Guillaume
Guillaume 2018-2-7
Well, then you use
[~, i1] = setdiff(t1(:, [1 2]), t2(:, [1 2]));
t3 = t1(i1, :)
Bradley Stiritz
Bradley Stiritz 2019-12-6
Hi Peter,
Your answer is very elegant, thank you. Do you have any thoughts please on also checking for differences in value vs. not-a-value status -- i.e. NaN, NaT ?
Would you recommend working along the lines of e.g. varfun(@isnan..)) ?
Thanks,
Brad

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更多回答（1 个）

Star Strider
Star Strider 2018-2-6
If I understand what you want to do, this will work:
Lv = ismember(t2, t1, 'rows');
DesiredRows = find(~Lv)
DesiredRows =
1
3
4
If not, reversing the arguments to ismember (link) will work.

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