r - 根据R中字符串的结尾创建新列

Question

我想根据字符串的结尾创建一个新列 Trial。例如，以数字 2 结尾的字符，如 A3-H2 或 A9-H2 将被视为 Trial 2 和那些不以 A3-H 或 A9-H 之类的数字结尾的将被视为试验 1。这应该是一个简单的 ifelse声明，但我不知道如何根据字符串的结尾来做。

它会从这个开始:

      Plant     Trtmt    
1:     SC       A3-H
2:     SC       A3-H2
3:     SC       A9-H
4:     SC       A9-H2

对此:

      Plant     Trtmt    Trial
1:     SC       A3-H       1
2:     SC       A3-H2      2
3:     SC       A9-H       1
4:     SC       A9-H2      2

真实数据:

dput(stack.df)
structure(list(Plant = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = c("SC", 
"W"), class = "factor"), Trtmt = c("A3-H", "A3-H", "A3-H", "A3-H", 
"A3-H", "A9-H", "A9-H", "A9-H", "A9-H", "A9-H", "A3-H2", "A3-H2", 
"A3-H2", "A3-H2", "A3-H2", "A9-H2", "A9-H2", "A9-H2", "A9-H2", 
"A9-H2")), .Names = c("Plant", "Trtmt"), row.names = c(6L, 7L, 
8L, 9L, 10L, 16L, 17L, 18L, 19L, 20L, 66L, 67L, 68L, 69L, 70L, 
76L, 77L, 78L, 79L, 80L), class = "data.frame")

Answer 1

library(tidyverse)

stack.df <- stack.df %>% 
  mutate(Trial = ifelse(grepl("2$", Trtmt), 2, 1))