Remove the last digits from numbers which exceed a certain length

Question

I have a vector of zip codes that includes both five and nine digit codes. I want to drop the end digits from codes which exceed a length of five.

For example, the following codes:

zip<-c(11566, 46235, 50467, 856073217, 97333, 856159229)

should become

zip
11566
46235
50467
85607
97333
85615

I was thinking gsub would be a good way to fix this, but I can't figure out how to write the code for it. I tried this but it definitely doesn't work.

df$zip<- gsub("\\d(!i:5)", "", as.character(df$zip))

Answer 1

This should work

zip<-c(11566, 46235, 50467, 856073217, 97333, 856159229)

> s <- substr(zip,1,5)
> s
[1] "11566" "46235" "50467" "85607" "97333" "85615"

> as.numeric(s)
[1] 11566 46235 50467 85607 97333 85615
>