Deleting repeated values in 2 matrices

Heya so I have a 22*2 and 25*2 matrix and I want to delete rows on both of them that have the same value on the 2nd column. So if theres say 1.25 on row 6 of A and 1.25 on row 8 of B is it possible to detect this and delete both rows?

Answer 1

[Cris LaPierre]

It's possible. Depending on what your requirements are, you might be interested in setdiff or ismember. Here's an example using ismember.

A = [rand(1,4);0:3]';
B = [rand(1,5);1:2:9]';

[indB,inA] = ismember(B(:,2),A(:,2))

indB = 5×1 logical array
   1
   1
   0
   0
   0

inA = 5×1

2 4 0 0 0

B(indB,:) = []

B = 3×2

0.2212 5.0000 0.3219 7.0000 0.6421 9.0000

A(inA(indB),:) = []

A = 2×2

0.4994 0 0.2882 2.0000

[Dyuman Joshi]

@Cris LaPierre, I would suggest to use ismembertol as OP is dealing with floating-point numbers.

[Cris LaPierre]

Agreed. Good point.

Answer 2

[Dyuman Joshi]

%logical indexing, use tolerance to compare floating point numbers
idx1 = abs(y1(:,2)-1.25)<1e-4);
idx2 = abs(y2(:,2)-1.25)<1e-4);
%deletion
y1(idx1,:)=[];
y2(idx2,:)=[];