See ?window.ts, e.g. > # 1 > tt <- ts(c(0.71, 0.63, 0.85, 0.44, 0.61, 0.69, 0.92, 0.55), + start = 1960, frequency = 4) > at <- c(1961, 3) > window(tt, at, at)[1] [1] 0.92
Note that 1961.00, 1961.25, 1961.50 and 1961.75 represent the 4 quarters of 1961 so this also works: # 2 > window(tt, 1961.5, 1961.5)[1] [1] 0.92 (Without the [1], the above commands return a time series of length 1 rather than just a number.) A third approach is to convert to zoo. as.zoo.ts converts a ts series to a zoo series whose index can be accessed via year + fraction notation and window.zoo supports an index argument (so we can avoid having to specify the index twice): > # 3 > library(zoo) > coredata(window(as.zoo(tt), index = 1961.5)) [1] 0.92 (Without coredata it returns a length 1 zoo series rather than just a number.) On Sat, Jan 30, 2010 at 9:22 AM, Dipankar Basu <basu...@gmail.com> wrote: > Hi All, > > I have a very simple question about a time series object: how to access > values for a particular year and quarter (say)? > > Suppose, following > > http://www.stat.pitt.edu/stoffer/tsa2/R_time_series_quick_fix.htm > > I have read in data as a time series; here is how it looks. > > * Qtr1 Qtr2 Qtr3 Qtr4 > 1960 0.71 0.63 0.85 0.44 > 1961 0.61 0.69 0.92 0.55 > . . . . . > . . . . . > 1979 14.04 12.96 14.85 9.99 > 1980 16.20 14.67 16.02 11.61* > > How do I access the value for 1961 quarter 3 (say)? > > Dipankar > > [[alternative HTML version deleted]] > > ______________________________________________ > 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.
