如何在dplyr Select in R中使用substr

substr(x, start, stop)

library(dplyr)

# 创建一个示例数据框
df <- data.frame(name = c("John Doe", "Jane Smith", "Mike Johnson"),
                 age = c(25, 30, 35),
                 city = c("New York", "London", "Paris"))

# 使用dplyr的select函数和substr来选择name列的前三个字符
df_subset <- df %>%
  select(name = substr(name, 1, 3))

# 输出结果
print(df_subset)

  name
1  Joh
2  Jan
3  Mik