在R中的另一个数据框中选择日期最接近特定日期的行

Question

我有两个数据框：

'df1' 列 - "ID" 和 "EVENT_DATE"

  ID    EVENT_DATE
  <chr> <date>    
1 ID001 2016-09-28
2 ID002 2011-03-15
3 ID003 2015-07-20

'df2' 列 - "ID"、"X" 和 "X_DATE"

   ID    X     X_DATE    
   <chr> <dbl> <date>    
 1 ID001  34.5 2015-04-25
 2 ID001  30   2015-08-25
 3 ID001  50.5 2016-01-20
 4 ID001  33   2016-09-25
 5 ID001  22   2016-09-29
 6 ID002  22   2010-02-20
 7 ID002  45   2011-02-24
 8 ID002  44   2012-02-13
 9 ID003  22   2015-05-15
10 ID003  34   2015-05-30
11 ID003  34   2015-07-12
12 ID003  43   2015-07-24

我想通过从 'df2'

中获取以下内容，为每个 ID 在 'df1' 中添加 "NEAREST_X_DATE" 和 NEAREST_X"

a) NEAREST_X_DATE = 'X_DATE which is nearest to EVENT_DATE'; NEAREST_X = 'X corresponding to NEAREST_X_DATE'

b) NEAREST_X_DATE = 'X_DATE which is nearest to EVENT_DATE but not later than EVENT_DATE'; NEAREST_X = 'X corresponding to NEAREST_X_DATE'

我应该如何进行此操作？感谢您的帮助。

Answer 1

这是一种可能性：

library(dplyr)

df1$EVENT_DATE <- as.Date(df1$EVENT_DATE)
df2$X_DATE <- as.Date(df2$X_DATE)

# a

df1 %>%
  left_join(df2) %>%
  mutate(diff = difftime(EVENT_DATE, X_DATE, units = "days")) %>%
  group_by(ID) %>%
  slice(which.min(abs(diff))) %>%
  rename(NEAREST_X = X, NEAREST_X_DATE = X_DATE) %>%
  select(-diff)

# b

df1 %>%
  left_join(df2) %>%
  mutate(diff = difftime(EVENT_DATE, X_DATE, units = "days")) %>%
  group_by(ID) %>%
  filter(diff >= 0) %>%
  slice(which.min(diff)) %>%
  rename(NEAREST_X = X, NEAREST_X_DATE = X_DATE) %>%
  select(-diff)

在R中的另一个数据框中选择日期最接近特定日期的行

Selecting row with date nearest to certain date in another data frame in R

r

lubridate

dplyr