unique函数如何仅返回dataframe中的唯一值？

我有dataframe，我想根据容器类型过滤每个站点在给定时间的容器数量。使用的数据包括放行和接收日期、到达站、唯一集装箱代码和集装箱类型。数据帧的一行是一个移动

library(dplyr)
library(tidyverse)
library(lubridate)

release.date <- as_date(c("2017-12-15","2018-05-31", "2017-03-03", "2017-11-16", "2017-10-15", "2017-12-22", "2017-12-02"))
receive.date <- as_date(c("2018-12-15","2018-08-31", "2017-09-03", "2017-12-16", "2017-11-15", "2017-12-24", "2017-12-02"))

Routen2 <- data.frame(release.date, receive.date, destination.station = c("New York", "London", "New York", "London", "New York", "New York", "New York"), container.code = c("A1", "B2", "B1", "B1", "B4", "B3", "A1"), container.type = c("a", "b", "b", "b", "b", "b", "a"))

---

在这个样本数据中，结果完全缺乏伦敦。container.code在unique函数之后不是唯一的（当脚本在没有最后两行的情况下运行时）。为什么不起作用？

不使用

基本R

函数（

顺序

，

唯一

），而使用

tidyverse

函数（

排列

，

不同

）可以在链中取代它。此外，

过滤器可以接受多个参数

library(tidyverse)
Routen2 %>% 
    filter(release.date <= "2017-12-31", receive.date <= "2017-12-31")  %>% 
    arrange(desc(release.date)) %>% 
    distinct(container.code, .keep_all = TRUE) %>% 
    count(destination.station, container.type)
# A tibble: 3 x 3
#  destination.station container.type     n
#  <fct>               <fct>          <int>
#1 London              b                  1
#2 New York            a                  1
#3 New York            b                  2

@谢谢，我在你的函数中添加了这个问题
  destination.station container.type     n  
1 New York            a                  1  
2 New York            b                  2  
3 London              b                  1

library(tidyverse)
Routen2 %>% 
    filter(release.date <= "2017-12-31", receive.date <= "2017-12-31")  %>% 
    arrange(desc(release.date)) %>% 
    distinct(container.code, .keep_all = TRUE) %>% 
    count(destination.station, container.type)
# A tibble: 3 x 3
#  destination.station container.type     n
#  <fct>               <fct>          <int>
#1 London              b                  1
#2 New York            a                  1
#3 New York            b                  2

Routen2 %>%
   filter(release.date <= "2017-12-31", receive.date <= "2017-12-31")%>%
  .[order(.$release.date),] %>% 
  .[!duplicated(.$container.code, fromLast = TRUE), ]