如何在最近的日期合并2个zoo/data.frame对象？

假设我有以下2个data.frames/zoo对象（您认为更容易使用的对象）：

注意：我更喜欢base-R实现

---

一种

基本R

方法是

# Converting date column into date format.
lookup.df[,"date"] <- as.Date(lookup.df[,"date"],"%m/%d/%Y")
main.df[,"date"] <- as.Date(main.df[,"date"],"%m/%d/%Y")

# Finding the index number under the defined condition.
index <- sapply(1:nrow(main.df), function(i){

        diff <- as.numeric(main.df[i,"date"] - lookup.df[,"date"])
        diff[diff<=0] <-NA
        which.min(diff)

        })

out <- data.frame(main.df,lookup.df[index,]) 

out[,c(1,3,2,4)]

---

从基R使用

findInterval

在

lookup.df

中查找每个

main.df

日期

findInterval

如果更改为

NA

的第二行中没有匹配的间隔so，则返回0，以便后续行返回此类值的NA，而不是删除它们

请注意，

lookup.df

在问题中是按日期顺序排序的，我们假设总是这样。如果不是，则首先对lookup.df进行排序

ix <- findInterval(main.df$date, lookup.df$date)
ix[ix == 0] <- NA
cbind(main = main.df, lookup = lookup.df[ix, ])

---

我第一次看到

findInterval（）

。。。好捷径！我的向上投票。添加了与此答案不匹配的处理，因为这有时发生在真实数据集中。

# Converting date column into date format.
lookup.df[,"date"] <- as.Date(lookup.df[,"date"],"%m/%d/%Y")
main.df[,"date"] <- as.Date(main.df[,"date"],"%m/%d/%Y")

# Finding the index number under the defined condition.
index <- sapply(1:nrow(main.df), function(i){

        diff <- as.numeric(main.df[i,"date"] - lookup.df[,"date"])
        diff[diff<=0] <-NA
        which.min(diff)

        })

out <- data.frame(main.df,lookup.df[index,]) 

out[,c(1,3,2,4)]

          date     date.1 value value.1
1   1999-01-10 1999-01-01    10       1
1.1 1999-02-01 1999-01-01    20       1
3   1999-03-10 1999-03-08    30       3
3.1 1999-04-02 1999-03-08    40       3
4   1999-06-01 1999-04-05    50       4

ix <- findInterval(main.df$date, lookup.df$date)
ix[ix == 0] <- NA
cbind(main = main.df, lookup = lookup.df[ix, ])

     main.date main.value lookup.date lookup.value
1   1999-01-10         10          NA           NA
1.1 1999-02-01         20  1999-01-01            1
3   1999-03-10         30  1999-03-08            3
3.1 1999-04-02         40  1999-03-08            3
4   1999-06-01         50  1999-04-05            4