示例中的Person_Id字段不匹配.

The Person_Id fields in your examples don't match.

我不确定这是否是您要使用的，但是我已经从您的dput()中创建了一个删除最后一列的文件:

I'm not sure if this is what you're after, but from your dput() I have created a file that removes the last column:

df_input <- df_output %>% 
  select(-Preceding_visit_id)

然后执行以下操作:

df_input %>% 
  group_by(Person_Id) %>% 
  mutate(Preceding_visit_id = lag(Visit_Id))

输出为:

# A tibble: 14 x 4
# Groups:   Person_Id [3]
   Person_Id Visit_Id Purpose Preceding_visit_id
       <dbl>    <dbl> <chr>                <dbl>
 1         1        1 checkup                 NA
 2         1        2 checkup                  1
 3         1        3 checkup                  2
 4         1        4 checkup                  3
 5         1        5 checkup                  4
 6         2        6 checkup                 NA
 7         2        7 checkup                  6
 8         2        8 checkup                  7
 9         2        9 checkup                  8
10         2       10 checkup                  9
11         2       11 checkup                 10
12         3       12 checkup                 NA
13         3       13 checkup                 12
14         3       14 checkup                 13