Remove specific values from array

Hi!

I have a vector with a lot of numbers, for example, A = [9,1,2,5,1,2,5,1,1,5,2,3,1,2,5,1,2,5,4,1,2,5,10]; and I want to remove all the values that are different from 1,2,5,9 or 10. In this case I would want to remove 3 and 4 so A would be

A = [9,1,2,5,1,2,5,1,1,5,2,1,2,5,1,2,5,1,2,5,10];

(I want to apply this to a vector with hundreds of values so I cannot remove that separately, I probably need do do a cycle but its not working)

How can I do this easily?

Answer 1

[DGM]

Something like this:

A = [9,1,2,5,1,2,5,1,1,5,2,3,1,2,5,1,2,5,4,1,2,5,10] % input
x = [1,2,5,9,10]; % values to keep
B = A(ismember(A,x))

[Adam Danz]

Also see ismembertol if you're working with floating point values.

[Ana Gabriela Guedes]

Thank you!!

[Ana Gabriela Guedes]

If I have a C vector that corresponds to A and want to remove the correspondents elements in C how can I do it?

So if I have A = [9,1,5,2,3,2] and C = [12,23,41,4,10,6] (for example)

I'll do as you said:

x = [1,2,5,9,]; % values to keep

B = A(ismember(A,x)) % B = [9,1,5,2,2]

and need to end up with an C = [12,23,41,4,6]

How can I remove in C the element that corresponds to the 3 in A?

[Adam Danz]

ismember(A,x) returns a logical index. Use that logical index to remove (or keep) values in both A and B.