Tensors: replacement if condition

I’m trying to replace the value of a tensor x when the value in x and the corresponding (i.e. at the same index) value in y are both zeros.
Being r the value I want to use for the substitution, I want to achieve something logically equivalent to: if x_i==0 and y_i == 0 then x_i = r.

I tried with something like x[x== 0 and y == 0] = r but it is not working.
What is the cleanest way to do this?
Thank you

Your solution is close. Instead of and, you should use &.

a = x==0
b = y==0
x[a & b] = r