named character question

Dear R People:

Here is a goofy question:

I want to extract the zip code from an address and here is my work  
so far:

add1

                 results.formatted_address
"200 W Rosamond St, Houston, TX 77076, USA"

add1[1][32:36]

<NA> <NA> <NA> <NA> <NA>
 NA   NA   NA   NA   NA

str(add1)

Named chr "200 W Rosamond St, Houston, TX 77076, USA"
- attr(*, "names")= chr "results.formatted_address"

> ttt <- "200 W Rosamond St, Houston, TX 77076, USA"

 > sub("^.+,.+,\\s[[:alpha:]]*\\s([[:digit:]]{5}).+", "\\1", ttt)
[1] "77076"

You will need to determine if all you addresses have two commas before  
the two letter state designation. You may not need as specific a  
pattern as this. An alternate pattern.

 > sub("^.+\\s[[:alpha:]]{2}\\s([[:digit:]]{5}).+", "\\1", ttt)
[1] "77076"

David Winsemius, MD
Alameda, CA, USA