How to create an empty R vector to add new items

I want to use R in Python, as provided by the module Rpy2. I notice that R has very convenient [] operations by which you can extract the specific columns or lines. How could I achieve such a function by Python scripts?

My idea is to create an R vector and add those wanted elements into this vector so that the final vector is the same as that in R. I created a seq(), but it seems that it has an initial digit 1, so the final result would always start with the digit 1, which is not what I want. So, is there a better way to do this?