Keep specific column variables and delete others?

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Tyla Ono
Tyla Ono 2018-8-18
评论： Walter Roberson 2023-4-1
Hi, I have a table with a list of column variables (Eg: [[Var1 Var2 Var3 Var4 VarN]. I am trying to keep only specific variables and associated column data, whilst deleting all others.
For example, I want only variable 2 and 4, while deleting all other columns. Desired output --> [Var2 Var4]
It is possible to output only the desired columns without individually deleting unwanted variables?

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采纳的回答

Paolo
Paolo 2018-8-18
Var1 = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Var2 = [38;43;38;40;49];
Var3 = logical([1;0;1;0;1]);
T = table(Var1,Var2,Var3)
To keep columns one and three:
T = [T(:,1) T(:,3)]
T =
5×2 table
Var1 Var3
_________ _____
'Sanchez' true
'Johnson' false
'Li' true
'Diaz' false
'Brown' true
Adapt the code for columns 2 and 4.

更多回答（1 个）

Alex Whiteway
Alex Whiteway 2022-5-19
I know this is a bit old, but I wanted to put my preferred method using column names:
Var1 = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Var2 = [38;43;38;40;49];
Var3 = logical([1;0;1;0;1]);
T = table(Var1,Var2,Var3)
%Keep just Var1 and Var3
Tnew = T(:,{'Var1', 'Var3'});
  2 个评论
Walter Roberson
Walter Roberson 2023-4-1
Ran in:
Testing efficiency:
Var1 = {'Sanchez';'Johnson';'Li';'Diaz';'Brown'};
Var2 = [38;43;38;40;49];
Var3 = logical([1;0;1;0;1]);
T = table(Var1,Var2,Var3)
T = 5×3 table
Var1 Var2 Var3 ___________ ____ _____ {'Sanchez'} 38 true {'Johnson'} 43 false {'Li' } 38 true {'Diaz' } 40 false {'Brown' } 49 true
%Keep just Var1 and Var3
tic; Tnew1 = T(:,{'Var1', 'Var3'}); toc
Elapsed time is 0.009980 seconds.
tic; Tnew2 = T(:,[1 3]); toc
Elapsed time is 0.006850 seconds.
tic; Tnew3 = [T(:,1), T(:,3)]; toc
Elapsed time is 0.037788 seconds.
So the {'Var1', 'Var3'} version is considerably more efficient than the [T(:,1), T(:,3)] option -- but it is not as efficient as indexing by variable numbers.

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