[R] Selecting vector elements using other vectors

Dear R-Help, I have a data frame and a vector df=data.frame(Letter=c("Z","Q","R","A","E","F"), Number=c(11,32,4,1,9,3)) v=c("C","Q","R","A","E") >From df, I'd like to construct a subset of the field "Number", with deletions dictated by the vector, v, of letters. I've succeeded in doing this fo

[R] timeSeries and aggregation() question

Hello, I've a time series, T, for an irregular sequence of days (data for bank holidays weekends have been removed). I would like to aggregate this series by into weeks using aggregate(x, by="weeks", FUN=mean). To do this, I think that x needs to be a timeSeries object, and when I try to call

[R] "xreg" in ARIMA modelling.

Hello, Does anyone know how the parameter estimates are calculated for xreg variables when called as part of an arima() command, or know of any literature that provides this info? In particular, I was wondering if there is a quick way to compare different combinations of "xreg" variables in the