如何根据type变量的值为var变量添加对应指定后缀？

首先还原你的数据框：

df <- 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"))

方法1：Base R 原生写法 #

直接用ifelse生成对应后缀，再通过paste0拼接：

df$new_var <- paste0(df$var, ifelse(df$type == "white", "_t", "_b"))

方法2：tidyverse（dplyr）写法 #

如果你习惯用tidyverse生态，用mutate配合条件判断即可：

library(dplyr)

# 用case_when（适合后续多条件扩展）
df <- df %>%
  mutate(new_var = paste0(var, case_when(type == "white" ~ "_t", type == "black" ~ "_b")))

# 仅两个条件时，用ifelse更简洁高效
df <- df %>%
  mutate(new_var = paste0(var, ifelse(type == "white", "_t", "_b")))

两种方法最终都会生成目标新列，结果示例：

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

内容的提问来源于stack exchange，提问作者a_todd12