An my "easy" but not very useful answer is that this particular subset probably violates some assumption of the cenros() model. I myself would start with simple inspections of the data, such as
with( subset(chem, param=='Ag'), table(ceneq1) ) with( subset(chem, param=='Ag'), qqnorm(quant) ) with( subset(chem, param=='Ag'), range(quant) ) in the hopes that something pops out. Do you have any zeros in quant? (see ?cenros) -Don -- Don MacQueen Lawrence Livermore National Laboratory 7000 East Ave., L-627 Livermore, CA 94550 925-423-1062 On 7/10/12 12:54 PM, "Rich Shepard" <rshep...@appl-ecosys.com> wrote: > Before reading water chemistry into a data frame I removed all missing >data. Yet when I try to run cenros() to summarize a specific chemical I >get >an error that I do not understand: > >with( subset(chem, param=='Ag'), cenros(quant,ceneq1) ) >Error in lm.fit(x, y, offset = offset, singular.ok = singular.ok, ...) : > NA/NaN/Inf in 'y' > > I would like to learn what I did incorrectly so I can avoid these >errors >in the future. > > The data frame structure is > >str(chem) >'data.frame': 120309 obs. of 8 variables: > $ site : Factor w/ 65 levels ";Influent","D-1",..: 2 2 2 2 2 2 ... > $ sampdate: Date, format: "2007-12-12" "2007-12-12" ... > $ preeq0 : logi TRUE TRUE TRUE TRUE TRUE TRUE ... > $ param : Factor w/ 37 levels "Ag","Al","Alk_tot",..: 1 2 8 17 3 9 ... > $ quant : num 0 0.106 1 231 231 0.011 0 0.002 0 100 ... > $ ceneq1 : logi FALSE FALSE TRUE FALSE FALSE FALSE ... > $ floor : num 0 0.106 0 231 231 0.011 0 0 0 100 ... > $ ceiling : Factor w/ 3909 levels "0.000","0.000)",..: 1 116 841 1771 >... > > I ran dput() on the data frame but cannot make sense of the output (a >5.5M >ASCII text file). > > Pointers appreciated. > >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. ______________________________________________ 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.