Inner_join 有两个条件和区间内的区间条件

Posted 2023-02-24

【中文标题】Inner_join 有两个条件和区间内的区间条件

【英文标题】：Inner_join with two conditions and interval within interval condition

【发布时间】：2018-10-17 04:40:13

【问题描述】：

尝试根据多个条件和时间间隔条件加入 2 个数据帧，如下例所示：

# two sample dataframes with time intervals
df1 <- data.frame(key1 = c("a", "b", "c", "d", "e"),
                   key2 = c(1:5),
                   time1 = as.POSIXct(hms::as.hms(c("00:00:15", "00:15:15", "00:30:15", "00:40:15", "01:10:15"))),
                   time2 = as.POSIXct(hms::as.hms(c("00:05:15", "00:20:15", "00:35:15", "00:45:15", "01:15:15")))) %>% 
  mutate(t1 = interval(time1, time2)) %>%
  select(key1, key2, t1)  

df2 <- data.frame(key1 = c("b", "c", "a", "e", "d"),
                   key2 = c(2, 6, 1, 8, 5),
                   sam1 = as.POSIXct(hms::as.hms(c("00:21:15", "00:31:15", "00:03:15", "01:20:15", "00:43:15"))),
                   sam2 = as.POSIXct(hms::as.hms(c("00:23:15", "00:34:15", "00:04:15", "01:25:15", "00:44:15")))) %>% 
mutate(t2 = interval(sam1, sam2)) %>%
select(key1, key2, t2)

需要对应的第一件事是列key1 和key2，可以通过以下方式完成（产生错误）：

df <- inner_join(df1, df2, by = c("key1", "key2"))

但是加入时还有一个条件需要检查，那就是间隔t2是否在t1之内。我可以像这样手动执行此操作：

 df$t2 %within% df$t1

我猜这个错误来自于以间隔连接数据帧，这可能不是正确的方法，这就是为什么会出现错误。

# desired dataframe
df <- data.frame(key1 = c("a", "b"), key2 = c(1,2), time_condition = c(TRUE, FALSE))

如果 t1 来自 "00:00:15" to "00:05:15"，则对应的 t2 即 "00:03:15" to "00:04:15" 将在间隔 t1 内。这将导致 time_condition 列，如果 t2 在 t1 内，则为 TRUE，否则为 FALSE。

【问题讨论】：

在连接的上下文中，一个区间在另一个区间内是什么意思？您能通过示例数据向我们展示吗？

帖子已被修改以澄清所请求的信息

【参考方案1】：

这个怎么样？

library(dplyr)

df1 %>%
  inner_join(df2, by = c("key1", "key2")) %>%
  filter(sam1 >= time1 & sam1 <= time2 & sam2 >= time1 & sam2 <= time2) %>%
  mutate(t1 = interval(time1, time2),
         t2 = interval(sam1, sam2)) %>%
  select(key1, key2, t1, t2)

输出为：

  key1 key2                                               t1                                               t2
1    a    1 1970-01-01 00:00:15 UTC--1970-01-01 00:05:15 UTC 1970-01-01 00:03:15 UTC--1970-01-01 00:04:15 UTC

样本数据：

df1 <- data.frame(key1 = c("a", "b", "c", "d", "e"),
                  key2 = c(1:5),
                  time1 = as.POSIXct(hms::as.hms(c("00:00:15", "00:15:15", "00:30:15", "00:40:15", "01:10:15"))),
                  time2 = as.POSIXct(hms::as.hms(c("00:05:15", "00:20:15", "00:35:15", "00:45:15", "01:15:15"))))

df2 <- data.frame(key1 = c("b", "c", "a", "e", "d"),
                  key2 = c(2, 6, 1, 8, 5),
                  sam1 = as.POSIXct(hms::as.hms(c("00:21:15", "00:31:15", "00:03:15", "01:20:15", "00:43:15"))),
                  sam2 = as.POSIXct(hms::as.hms(c("00:23:15", "00:34:15", "00:04:15", "01:25:15", "00:44:15"))))

【参考方案2】：

使用 data.table，您可以在加入时执行操作。这是一个例子

library(data.table)
df2[df1, # left join
    .(time_condition = sam1 > time1 & sam2 < time2), # condition while joining
    on = .(key1, key2), # keys
    by = .EACHI, # check condition per join
    nomatch = 0L] # make it an inner join

#    key1 key2 time_condition
# 1:    a    1           TRUE
# 2:    b    2          FALSE

---

# your data generated using data.table

df1 <- data.table(key1 = c("a", "b", "c", "d", "e"),
                  key2 = c(1:5),
                  time1 = as.ITime(c("00:00:15", "00:15:15", "00:30:15", "00:40:15", "01:10:15")),
                  time2 = as.ITime(c("00:05:15", "00:20:15", "00:35:15", "00:45:15", "01:15:15"))) 
df2 <- data.table(key1 = c("b", "c", "a", "e", "d"),
                  key2 = c(2, 6, 1, 8, 5),
                  sam1 = as.ITime(c("00:21:15", "00:31:15", "00:03:15", "01:20:15", "00:43:15")),
                  sam2 = as.ITime(c("00:23:15", "00:34:15", "00:04:15", "01:25:15", "00:44:15")))

【参考方案3】：

您可以使用内置函数 merge() 进行连接。

df =  merge(df1, df2, by = c("key1", "key2"))
df = data.frame(df[,c("key1", "key2")], time_condition = df$t2 %within% df$t1)
df
#  key1 key2 time_condition
#1    a    1           TRUE
#2    b    2          FALSE

谢谢