adding xts time series
Your issue is caused by xts merging objects before performing math operations.
x <- .xts(1:10,1:10) x[10]-x[9] # empty xts object
Data: integer(0) Index: NULL
x[10]-lag(x)[10] # this aligns the index before subtracting
[,1] 1969-12-31 18:00:10 1 Be careful to note that your solution works because the "[[" function does not return an xts object, so using "[[" may cause issues if you use it when you do expect / need an xts object returned. Best, -- Joshua Ulrich FOSS Trading: www.fosstrading.com On Sat, Aug 21, 2010 at 4:58 PM, Nick Torenvliet
<nick.torenvliet at gmail.com> wrote:
myPrediction[10,1]<- myPrediction[[10,1]]-myPrediction[[9,1]] phhhhhttt!! On Sat, Aug 21, 2010 at 5:28 PM, Nick Torenvliet <nick.torenvliet at gmail.com>wrote:
An obviously dumb question but I'm trying to add/subtract xts data...
myPrediction[10]<- myPrediction[10]-myPrediction[9]
Error in NextMethod(.Generic) : replacement has length zero
myPrediction[10,1]<- myPrediction[10,1]-myPrediction[9,1]
Error in NextMethod(.Generic) : replacement has length zero
myPrediction[10,1] <- (myPrediction[10,1]-myPrediction[9,1])
Error in NextMethod(.Generic) : replacement has length zero
is.xts(myPrediction)
[1] TRUE
myPrediction[10]
Nov 2009 9854.299
myPrediction[9]
Oct 2009 9713.752 What is my issue here?
? ? ? ?[[alternative HTML version deleted]]
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