以另一个变量为条件向变量值添加后缀

我们可以使用 dplyr::case_when() :

library(tidyverse)

dat %>% 
  mutate(var = case_when(type == "white" ~ paste0(var, "_t"),
                         type == "black" ~ paste0(var, "_b"))
         )
#> # A tibble: 6 × 2
#>   var     type 
#>   <chr>   <chr>
#> 1 test_t  white
#> 2 test_b  black
#> 3 score_t white
#> 4 score_b black
#> 5 base_t  white
#> 6 base_b  black

来自OP的数据

dat <- structure(list(var = c("test", "test", "score", "score", "base", 
                       "base"),
               type = c("white", "black", "white", "black", "white", 
                                         "black")),
          row.names = c(NA, -6L),
          class = c("spec_tbl_df", "tbl_df", "tbl", "data.frame"))

^{创建于2023-02-20 reprex v2.0.2}

另一个选项 tidyverse

library(dplyr)
library(stringr)
df1 %>% 
  mutate(var = str_c(var, substr(str_replace(type, "^w", "t"), 1, 1), sep = '_'))

-输出

# A tibble: 6 × 2
  var     type 
  <chr>   <chr>
1 test_t  white
2 test_b  black
3 score_t white
4 score_b black
5 base_t  white
6 base_b  black