合并两个向量为一组创建重复项

Question

我希望合并两个向量（时间和位置）以创建一个包含每个位置的所有时间的数据框。下面是两个向量：

#Here are the hours
    base_hours = seq(
      from=as.POSIXct("2015-1-1 0:00", tz="America/New_York"),
      to=as.POSIXct("2015-1-3 23:00", tz="America/New_York"),
      by="hour"
    )

 #hypothetical locations
    loc = c("woodside", "corona", "jackson heights", "flushing")

如何合并它们以便每个地点的每个日期都以基准时间为单位？最后一组看起来像这样：

loc              hours
woodside          2015-01-01 00:00:00 EST
woodside          2015-01-01 01:00:00 EST
woodside          2015-01-01 02:00:00 EST
corona            2015-01-01 00:00:00 EST
corona            2015-01-01 01:00:00 EST
corona            2015-01-01 02:00:00 EST

Answer 1

如果我理解正确的话，这样的事情会起作用：

>final <- merge(loc, base_hours)
>colnames(final) <- c("loc","hours")
>final
            *loc               hours
1          woodside 2015-01-01 00:00:00
2            corona 2015-01-01 00:00:00
3   jackson heights 2015-01-01 00:00:00
4          flushing 2015-01-01 00:00:00
5          woodside 2015-01-01 01:00:00
6            corona 2015-01-01 01:00:00
7   jackson heights 2015-01-01 01:00:00
8          flushing 2015-01-01 01:00:00
9          woodside 2015-01-01 02:00:00
10           corona 2015-01-01 02:00:00
11  jackson heights 2015-01-01 02:00:00

Answer 2

我们可以使用expand.grid

res <- expand.grid(loc = loc, base_hours = base_hours)
head(res)
#              loc          base_hours
#1        woodside 2015-01-01 00:00:00
#2          corona 2015-01-01 00:00:00
#3 jackson heights 2015-01-01 00:00:00
#4        flushing 2015-01-01 00:00:00
#5        woodside 2015-01-01 01:00:00
#6          corona 2015-01-01 01:00:00

或 CJ 来自 data.table

library(data.table)
CJ(loc=loc, base_hours=base_hours)

合并两个向量为一组创建重复项

merge two vectors to create duplicates for one group

merge

r

date

seq