Last characters of a data.frame column in R

Question

I have a table within a date.frame, and I need to get only the last two characters of that table, how do I do that?

bs.: I was trying to do it using str_sub, but in it I can only define which character starts and which ends, and my data varies the character size. Follow my example below that does not solve:

base$estado <- str_sub(psd_base$itbc_name, start = 2)

Answer 1

A simple way to do this with R base is through the command substr. With it, I can extract a substring indicating where it begins and where it ends.

Let’s look at two practical examples, with the names Joao and Maria:

Joao
1234

Maria
12345

To extract ao of Joao, the substr need to extract characters 3 and 4. To extract ia of Mary, the command substr need to extract characters 4 and 5. It is easy to see that both drawings start in the penultimate character (nchar(Joao) - 1) and end at the last character (nchar(Joao)). Similarly, (nchar(Maria) - 1) and (nchar(Maria)).

Automating this, we have the code below:

x <- c("Joao", "Maria", "Pedro", "Juliana")

substr(x, start = nchar(x)-1, stop = nchar(x))
#> [1] "ao" "ia" "ro" "na"

^{Created on 2020-07-10 by the reprex package (v0.3.0)}