r-通过最接近的匹配将两个数据帧连接起来

Question

我有两个大型数据集，唯一共享的功能是数字时间戳。我想按这个时间戳合并数据帧，但数据收集的频率并不完全匹配，所以我需要允许它与最接近的匹配项合并。

作为一个简化的示例，这里有一个小数据集，其中包含一个值列、一些事件和一个ID:

a<-c("150", "164", "175", "183", "195", "200", "205","213")
b<-c("start1","end1","start2", "end2", "start1", "end1", "start2", "end2")
c<-c("A","A","A", "A", "B", "B", "B", "B")
(data<-data.table(value = a, event = b, ID = c))

我希望能够将这个"；数据"；用这个数值系列("次数"(乘以值列：

(times<-data.frame(value = c(seq(from = 150, to = 213, by = 3))))

因此，它们通过值列中最接近的近似匹配进行合并，以产生最终的数据帧：

agoal<-c(seq(from = 150, to = 213, by = 3))
bgoal<-c("start1","","","","","end1","", "",
"start2", "", "", "end2", "", "", "",
"start1", "", "end1", "start2", "", "", "end2")
cgoal<-c("A","","","","","A","", "",
"A", "", "", "A", "", "", "",
"B", "", "B", "B", "", "", "B")
(goal<-data.frame(value = agoal, event = bgoal, ID = cgoal))

有没有办法做到这一点，尤其是对于一个非常大的数据集(这样它就不会崩溃R(？

Answer 1

data.table提供了滚动联接解决方案。

library(data.table)
setkey(data,value)
setkey(times,value)
data[times,roll = "nearest"]
#    value  event ID
# 1:   150 start1  A
# 2:   153 start1  A
# 3:   156 start1  A
# 4:   159   end1  A
# 5:   162   end1  A
# 6:   165   end1  A
# 7:   168   end1  A
# 8:   171 start2  A
# 9:   174 start2  A
#10:   177 start2  A
#11:   180   end2  A
#12:   183   end2  A
#13:   186   end2  A
#14:   189   end2  A
#15:   192 start1  B
#16:   195 start1  B
#17:   198   end1  B
#18:   201   end1  B
#19:   204 start2  B
#20:   207 start2  B
#21:   210   end2  B
#22:   213   end2  B

数据：

a<-c("150", "164", "175", "183", "195", "200", "205","213")
b<-c("start1","end1","start2", "end2", "start1", "end1", "start2", "end2")
c<-c("A","A","A", "A", "B", "B", "B", "B")
data<-data.table(value = as.numeric(a), event = b, ID = c)
times<-data.table(value = c(seq(from = 150, to = 213, by = 3)))

Answer 2

要通过最接近的匹配进行连接，而不需要用近似匹配来填补空白，fuzzyjoin效果很好！

(end<-fuzzyjoin::difference_left_join(times, data, by = "value", max_dist = 1, distance_col= "distance"))