r - 日期选择的逻辑

Question

我一直在用 R 编写这个逻辑。有人可以帮我写这个逻辑吗？

逻辑:

(Priority1) For an Item, Date1 == Calendar then we have to select that row. Eg - Item B

(Priority2) For an Item if not Priority1 then, Date1 ~ Previous date in Calendar column then select that row. Eg - Item C

(Priority3) For an Item if not Priority1 & 2 then, Date1 ~ Next date in Calendar column then select that row. Eg - Item A

输入:

Item   Date1     Calendar
A   2021-01-08  2021-01-11
A   2021-01-08  2021-01-19
B   2021-02-05  2021-01-29
B   2021-02-05  2021-02-05
B   2021-02-05  2021-02-12
C   2021-02-15  2021-02-07
C   2021-02-15  2021-02-13
C   2021-02-15  2021-02-20
C   2021-02-15  2021-02-27

这是dput数据的

input <- structure(list(Item = c("A", "A", "B", "B","B", "C", "C","C","C"), Date1 = c("2021-01-08", 
                                                            "2021-01-08", "2021-02-05", "2021-02-05", "2021-02-05", "2021-02-15", "2021-02-15", "2021-02-15", "2021-02-15"), Calendar = c("2021-01-11", "2021-01-19", "2021-01-29", "2021-02-05","2021-02-12", "2021-02-07","2021-02-13", "2021-02-20", "2021-02-27")), class = "data.frame", row.names = c(NA, -9L))

输出:

Item   Date1     Calendar
A   2021-01-08  2021-01-11
B   2021-02-05  2021-02-05
C   2021-02-15  2021-02-13

这是dput预期输出。

output <- structure(list(Item = c("A","B", "C"), Date1 = c("2021-01-08","2021-02-05", "2021-02-15"), Calendar = c("2021-01-11","2021-02-05","2021-02-13")), class = "data.frame", row.names = c(NA, -3L))

Answer 1

这是另一种tidyverse方法。计算 Date1 和 Calendar 之间的绝对差。然后，根据上述规则分配优先级值(对于优先级 1、2 或 3)。然后，根据优先级和天数差异进行排序。最后，对于每个组，取第一行(最高优先级，基于规则和最近的日期)。

library(tidyverse)

input$Date1 <- as.Date(input$Date1)
input$Calendar <- as.Date(input$Calendar)

input %>%
  mutate(Diff = abs(Date1 - Calendar)) %>%
  group_by(Item) %>%
  mutate(Priority = case_when(
    Diff == 0 ~ 1,
    Date1 > Calendar ~ 2,
    TRUE ~ 3
  )) %>%
  arrange(Priority, Diff) %>%
  slice(1)

输出

  Item  Date1      Calendar   Diff   Priority
  <chr> <date>     <date>     <drtn>    <dbl>
1 A     2021-01-08 2021-01-11 3 days        3
2 B     2021-02-05 2021-02-05 0 days        1
3 C     2021-02-15 2021-02-13 2 days        2