The problem is that the acf function (like many R functions) returns a list containing many different things. For example, I have a short series in the vector z:
> acz <- acf(z) > str(acz) List of 6 $ acf : num [1:11, 1, 1] 1 -0.0668 -0.7401 0.0627 0.5954 ... $ type : chr "correlation" $ n.used: int 11 $ lag : num [1:11, 1, 1] 0 1 2 3 4 5 6 7 8 9 ... $ series: chr "z" $ snames: NULL - attr(*, "class")= chr "acf" Let's say you are interested in extracting the acf and lag values from that > acd <- data.frame(cbind(lag=acz$lag,acf=acz$acf)) > acd lag acf 1 0 1.00000000 2 1 -0.06676557 3 2 -0.74006273 4 3 0.06266564 5 4 0.59542482 6 5 -0.06786556 7 6 -0.41370293 8 7 0.03464621 9 8 0.21887326 10 9 -0.07485743 11 10 -0.04835570 ______________________________________________ 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.