r - 根据R中其他列中的条件将数字附加到列中的字符串

Question

我想根据以下条件在 course 列中仅向 MATH 添加一个数字；对于每个 ID 如果 MATH 的 output 列等于 pass 将下一个 的附加数字增加 1 >数学。这是一个例子:

df = read.table(text = 
'ID  course  outcome
 10  MATH    fail
 10  PHYS    pass
 10  MATH    pass
 10  MATH    fail
 10  CHEM    pass
 11  MATH    pass
 11  PHYS    fail
 12  CMP     pass
 12  MATH    fail
 12  MATH    fail
 12  CHEM    pass
 12  MATH    pass
 12  MATH    fail', header = T)


df_result = read.table(text = 
  'ID  course  outcome
   10  MATH1    fail
   10  PHYS     pass
   10  MATH1    pass
   10  MATH2    fail
   10  CHEM     pass
   11  MATH1    pass
   11  PHYS     fail
   12  CMP      pass
   12  MATH1    fail
   12  MATH1    fail
   12  CHEM     pass
   12  MATH1    pass
   12  MATH2    fail', header = T)

请帮我用R做

Answer 1

像这样的东西应该可以解决问题(使用 dplyr):

df %>% 
  group_by(ID) %>%
  mutate(math_pass_count = 1 + lag(cumsum(course == "MATH" & outcome == "pass"), 
                                   default = 0),
         suffix = ifelse(course == "MATH", math_pass_count, ""),
         course = paste0(course, suffix)) %>%
  select(-math_pass_count, -suffix)