Replacing the zero entry of a vector with the corresponding entry of another vector of the same dimension.

Hello everyone,

Please I need some help about this:

Suppose I have 2 vectors A=[0;2;0] and B=[3;5;7]. How can I write a command in MATLAB that simply replace the zero entries of vector A with the corresponding non-zero entries of vector B?

In general, if I have 2 vectors A and B of the same dimension, assuming vector A have some zero entries, but the vector B have no zero entries. How can I replace the all the zero entries of vector A with that of the corresponding entries of vector B?

Thanks for any help.

Answer 1

[Birdman]

A(A==0)=B(A==0)

[Hassan]

Thanks for the nice answer. Please, could explain more about the RHS? i.e. B(A==0)

[Birdman]

A==0

This is logical indexing. It returns 1 for the elements that are zero, and 0 for the elements that are not. By the power of MATLAB, we can easily use this boolean output to obtain indexes for the zero elements of a in B vector as follows:

B(A==0)

This is equivalent to

idx=find(A==0);
A(idx)=B(idx);

but my initial answer is more efficient and faster.

[Hassan]

Of course. Thank you Mr. Birdman.