Hi,
I tried to google for any solution for asof join operator in R. But I
couldn't find one. The asof join operator AsOf(A,B) merges 2 time
series by looking for latest available value of B prior to each time
point in A. For example,
A <- xts(c(10,15,20,25),
order.by=as.POSIXct(c("2011-09-01","2011-09-09","2011-09-10","2011-09-15"))
B <- xts(c(1.1,1.5,1.3,1.7),
order.by=as.POSIXct(c("2011-08-31","2011-09-09","2011-09-11","2011-09-12"))
AsOf(A,B) should return
A B
2011-09-01 10 1.1
2011-09-09 15 1.1 # (because latest value B prior to
2011-09-09 is 1.1)
2011-09-10 20 1.5
2011-09-15 25 1.7
How do I write the above AsOf function in R? The merge function does
not do what I want because it will align points that have the same
time stamp together while what I want is actually latest value prior
to timestamp in A. Any example would be greatly appreciated. Thank
you.
Cheers,
Robert
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