Get all unique combinations of 2 columns from a table

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I have a table that has 4 variables, similar to this:
Item1 Item2 Item3 Item4
_____ _____ _____ _____
1 5 7 10
What is the best way to produce the delta of each combination of columns? Ex. Item1 vs Item2, Item1 vs Item3, etc.

Accepted Answer

Stephen23
Stephen23 on 19 Jan 2022
V = {'Item1','Item2','Item3','Item4'};
T = table(1, 5, 7 ,10, 'VariableNames',V)
T = 1×4 table
Item1 Item2 Item3 Item4 _____ _____ _____ _____ 1 5 7 10
X = nchoosek(1:numel(V),2);
D = diff(T{:,V}(X),1,2);
Z = cell2table([V(X),num2cell(D)])
Z = 6×3 table
Var1 Var2 Var3 _________ _________ ____ {'Item1'} {'Item2'} 4 {'Item1'} {'Item3'} 6 {'Item1'} {'Item4'} 9 {'Item2'} {'Item3'} 2 {'Item2'} {'Item4'} 5 {'Item3'} {'Item4'} 3

More Answers (1)

Cris LaPierre
Cris LaPierre on 19 Jan 2022
I would look into using the perms function, along with the unique and diff functions.
  3 Comments
Cris LaPierre
Cris LaPierre on 19 Jan 2022
I was probably trying too hard to make use of the variablenames. Stephen's approach is simpler by using column numbers instead.
T = table(1, 5, 7 ,10, 'VariableNames', {'Item1' 'Item2' 'Item3' 'Item4'});
C = nchoosek(T.Properties.VariableNames,2)
C = 6×2 cell array
{'Item1'} {'Item2'} {'Item1'} {'Item3'} {'Item1'} {'Item4'} {'Item2'} {'Item3'} {'Item2'} {'Item4'} {'Item3'} {'Item4'}
delta = diff([T{1,{C{:,1}}};T{1,{C{:,2}}}])
delta = 1×6
4 6 9 2 5 3
Austin Burritt
Austin Burritt on 19 Jan 2022
His and yours are both excellent and elegant, thank you!

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