On Tue, 13 Sep 2011, Gabor Grothendieck wrote:
As in ?zoo a zoo object is a numeric matrix, numeric vector or factor together with an ordered time index which is unique. Its not clear that that is what you have; however, if we can assume that for each value of param we have a unique set of dates then quant could form a multivariate zoo series with Date index.
Gabor, Perhaps, then, zoo is not the appropriate library for my needs. Let me try to clarify; being new to R and certainly new to zoo I may not express myself clearly to those of you who are more experienced. On a given date (sampdate) and a given stream (aggregated from multiple locations on that stream) a water sample was sent to the laboratory and analyzed for a set of chemicals (param). Each param does not have a unique set of dates. As my example showed, on 2010-06-30 SO4, Zn, and As concentrations were measured on Winters Creek. On 2011-06-06, Cl, SO4, and Zn concentrations were measured on the same stream.
Read over ?zoo and ?read.zoo and also the 5 vignettes. The zoo-read vignette is entirely about read.zoo. If you really do want to keep all that info you might want to use a data frame instead or possibly several zoo objects.
The data are already in a data.frame and I need both factors and the date to interpret the numeric values. I read ?zoo, but not ?read.zoo. I'll have to search for the vignettes. Thanks, Rich ______________________________________________ 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.
