如何在 R 中分组和取消分组？

Question

我有一个如下所示的数据框

test_df <- data.frame("SN" = c("ABC123","ABC123","ABC123","MNO098","MNO098","MNO098"), 
                      "code" = c("ABC1111","DEF222","GHI133","","MNO1123","MNO567"), 
                      "d_time" = c("2220-08-27","2220-05-27","2220-02-27","2220-11-27","2220-02-27",""))

我正在尝试做两件事

1) 通过从列 SN 和 code 中删除字母创建 2 个新列 (p_id,v_id) 并仅保留 9 位数字

2) 基于 v_id 为基于 his/her d_time

排序的每个人创建滞后列 (p_vid)

t_df <- test_df %>% group_by(SN)
t_df %>% arrange((d_time), .by_group = TRUE) ->> sorted_df #sorted based on d_time
transform_ids = function(DF){  # this function is to create person and visit_occurrence ids
  DF %>% 
    mutate(p_id = as.integer(str_remove_all(.$SN,"[a-z]|[A-Z]") %>%   #retaining only the numeric part
                                    str_sub(1,9))) %>%
    mutate(v_id = as.integer(str_remove_all(.$code,"[a-z]|[A-Z]") %>% 
                                              str_sub(1,9))) %>%
    group_by(p_id) %>%
    mutate(pre_vid = lag(v_id)) %>%
    ungroup
}
transform_ids(sorted_df)

但是当我这样做时，我遇到了以下错误

Error in View : Column p_id must be length 3 (the group size) or one, not 6 Error: Column p_id must be length 3 (the group size) or one, not 6 In addition: Warning message: In view(transform_ids(t_df)) : Show Traceback Rerun with Debug Error: Column p_id must be length 3 (the group size) or one, not 6

我希望我的输出如下所示。基本上我试图 link 一个人的每个 v_id 到他以前的访问，即 p_vid

Answer 1

要生成 p_id 和 v_id 列，只需使用 sub:

t_df$p_id <- gsub("[A-Z]+", "", t_df$SN)
t_df$v_id <- gsub("[A-Z]+", "", t_df$code)

对于 p_vid 列，使用 dplyr 包中的 lag()：

t_df %>%
group_by(p_id) %>%
mutate(p_vid = lag(v_id, order_by=d_time, default=0))

上面的输出实际上给了你一个提示。如果你想要一个数据框，只需使用：

t_df <- as.data.frame(t_df)

输出：

  SN     code    d_time     p_id  v_id  p_vid
  <fct>  <fct>   <fct>      <chr> <chr> <chr>
1 ABC123 ABC1111 2220-08-27 123   1111  222  
2 ABC123 DEF222  2220-05-27 123   222   133  
3 ABC123 GHI133  2220-02-27 123   133   0    
4 MNO098 ""      2220-11-27 098   ""    1123 
5 MNO098 MNO1123 2220-02-27 098   1123  567  
6 MNO098 MNO567  ""         098   567   0

如何在 R 中分组和取消分组？

How to group and ungroup in R?

r

dataframe

dplyr

purrr

tibble