如何根据 R 中的最后一个字符对字符串向量进行排序

Question

I want to sort a vector of strings based on the last character in R. Lets say I have m

m <- names(df)
m
[1] "test_1_p" "test_2_n" "test_3_p" "test_4_p" "test_5_n"

For reproduciblity:

m <- c("test_1_p","test_2_n","test_3_p","test_4_p","test_5_n")

Now my Desired output would be

[1] "test_2_n" "test_5_n" "test_1_p" "test_3_p" "test_4_p" 

I tried to work with strsplit , but couldn't get it to work

r = strsplit(m,"_")
sorting_df = data.frame(r)
sort(sorting_df[3,])

I belief there has to be a fairly simple solution to that comparable to python where one could easily do it like this

lst = ["test_1_p","test_2_n","test_3_p","test_4_p","test_5_n"]
sorted(lst, key=lambda x: x[-1])

Edit All provided Solutions work thank you very much. Just accepted the first one.

Answer 1

You can get the last part from the string and use it's order to subset the string.

m[order(sub('.*_', '', m))]
#[1] "test_2_n" "test_5_n" "test_1_p" "test_3_p" "test_4_p"

Answer 2

Does this work:

m[order(substr(m,nchar(m),nchar(m)))]
[1] "test_2_n" "test_5_n" "test_1_p" "test_3_p" "test_4_p"

Answer 3

Here is a solution with funprog::sort_by :

lastChar <- function(str){
  substr(str, nchar(str), nchar(str))
}
library(funprog)
sort_by(m, lastChar)

Answer 4

We can use stri_extract_last

library(stringi)
m[order(stri_extract_last(m, regex = "\\w"))]
#[1] "test_2_n" "test_5_n" "test_1_p" "test_3_p" "test_4_p"