Exclude elements from array [duplicate]

问题:

This question already has answers here:

How do I remove elements at a set of indices in a vector in MATLAB? (1 answer)

Retrieving the elements of a matrix with negated exact indexing with index matrix? (2 answers)

Closed 6 years ago.

I have a column vector:

A = [1; 2; 3; 4; 4; 5; 5; 7]; 

I wish to exclude the elements of A that are in a second matrix B:

B = [4; 5]

The final result should be:

A = [1; 2; 3; 7]

I am pretty sure using MATLAB elegant syntaxing, this be accomplished without writing a for loop, but not sure how?

回答1:

I would use Afilt=A(~ismember(A,B));. This will return all elements of A which are not in B.

回答2:

You can compare values with bsxfun:

A = A(all(bsxfun(@ne, A(:), B(:).'), 2))

This approach is especially good if you need to handle floating-point numbers (whereismember fails):

A(all(abs(bsxfun(@minus, A(:), B(:).')) >= eps, 2))

Instead of eps, you can set any tolerance threshold you want.

回答3:

EDIT: If you want to remove row 4 and 5 it is this, if you want to remove the rows with fours and fives check the other answers.

Simple as this

A = [1; 2; 3; 4; 4; 5; 5; 7];     
B = [4; 5];

A(B)=[];