lag and as.ts are separate operations (which in fact commute) > lag(as.ts(1:10), 1) Time Series: Start = 0 End = 9 Frequency = 1 [1] 1 2 3 4 5 6 7 8 9 10
> as.ts(lag(1:10, 1)) Time Series: Start = 0 End = 9 Frequency = 1 [1] 1 2 3 4 5 6 7 8 9 10 > You do NOT need to call as.ts at all it that's your bent: > lag(1:10, 1) [1] 1 2 3 4 5 6 7 8 9 10 attr(,"tsp") [1] 0 9 1 but as lag is an operation designed for time series objects, it's a pretty good bet that to make any sense of the result you need to start (or end up) with a time series object. The key is the concept of an 'object' in R. You need to know what kind of objects you are dealing with. -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of eric Sent: Wednesday, 19 January 2011 1:08 PM To: r-help@r-project.org Subject: Re: [R] Log difference in a dataframe column Just learning so excuse me if I'm being too basic here. But I'm wondering how should I know that as.ts would be needed for lag ? Is there a thought process or way to inspect that I should have gone through to know that log would work on y[,5] but lag would not work on [,5] ? Is the general rule that lag is not in the base package and therefore would not work ? Thanks for the comments -- View this message in context: http://r.789695.n4.nabble.com/Log-difference-in-a-dataframe-column-tp3221225p3224478.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
