r - 根据日期创建列

Question

我有类似以下的数据，但更大

boat = c(1,1,1,1,1,1,1,2,2,2,2,2,2)
species = c("cod", "haddock", "ling", 
       "cod", "haddock", "ling", "tusk", 
       "cod", "haddock", "ling",
       "cod", "haddock", "ling")
date = c(as.Date(c("1.03.2017","1.03.2017","1.03.2017",
               "2.03.2017", "2.03.2017", "2.03.2017","2.03.2017",
               "4.03.2017","4.03.2017","4.03.2017",
               "7.03.2017", "7.03.2017", "7.03.2017"), "%d.%m.%Y"))
df <- data.frame(boat, species, date)

    df
    boat  species  date
    1     cod      01.03.2017
    1     haddock  01.03.2017
    1     ling     01.03.2017
    1     cod      02.03.2017
    1     haddock  02.03.2017
    1     ling     02.03.2017
    1     tusk     02.03.2017
    2     cod      04.03.2017
    2     haddock  04.03.2017
    2     ling     04.03.2017
    2     cod      07.03.2017
    2     haddock  07.03.2017
    2     ling     07.03.2017

我想创建一个附加列，按船顺序排列日期，以便我的数据集如下所示。

    boat  species  date       rank
    1     cod      01.03.2017 1
    1     haddock  01.03.2017 1
    1     ling     01.03.2017 1
    1     cod      02.03.2017 2
    1     haddock  02.03.2017 2
    1     ling     02.03.2017 2
    1     tusk     02.03.2017 2
    2     cod      04.03.2017 1
    2     haddock  04.03.2017 1
    2     ling     04.03.2017 1
    2     cod      07.03.2017 2
    2     haddock  07.03.2017 2
    2     ling     07.03.2017 2

我试过下面的代码

library(dplyr)

df %>% 
group_by(boat, species) %>% 
mutate(Order = rank(date))

但是以前没有出现过的物种在第一次出现时会被赋予“1”级。任何帮助表示赞赏。

Answer 1

我们可以使用 dplyr 中的 group_by 和 dense_rank 来创建所需的输出。

library(dplyr)

df2 <- df %>%
  group_by(boat) %>%
  mutate(rank = dense_rank(date))

df2
# A tibble: 13 x 4
# Groups:   boat [2]
    boat species       date  rank
   <dbl>  <fctr>     <date> <int>
 1     1     cod 2017-03-01     1
 2     1 haddock 2017-03-01     1
 3     1    ling 2017-03-01     1
 4     1     cod 2017-03-02     2
 5     1 haddock 2017-03-02     2
 6     1    ling 2017-03-02     2
 7     1    tusk 2017-03-02     2
 8     2     cod 2017-03-04     1
 9     2 haddock 2017-03-04     1
10     2    ling 2017-03-04     1
11     2     cod 2017-03-07     2
12     2 haddock 2017-03-07     2
13     2    ling 2017-03-07     2