Thanks for your comprehensive explanation. Recent changes exposed errors in my code (and understanding!). Murray
________________________________________ From: Sebastian Meyer <seb.me...@fau.de> Sent: 30 June 2022 20:19 To: Murray Efford Cc: r-devel@r-project.org Subject: Re: [Rd] Problem with contrasts bug fix? For reference: this is about <https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fbugs.r-project.org%2Fshow_bug.cgi%3Fid%3D17616&data=05%7C01%7Cmurray.efford%40otago.ac.nz%7Cad75da3bbad346a7d0c108da5a715362%7C0225efc578fe4928b1579ef24809e9ba%7C0%7C0%7C637921740057400452%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=XOLVFd9sZKQKebLOj%2BiIN%2FmNnvLNSNKdzakHHZXX2O4%3D&reserved=0>. The problem with your 'contr.none' example is that it is not a proper contrasts function (and has never been). ?contrasts says > Suitable > functions have a first argument which is the character vector of > levels, a named argument 'contrasts' (always called with > 'contrasts = TRUE') and optionally a logical argument 'sparse'. Your example function fails also in R 4.1.3 and 4.2.1: > contr.none <- function(n) contrasts(factor(1:n), contrasts = FALSE) > contrasts(CO2$Treatment) <- "contr.none" > contrasts(CO2$Treatment) Error in ctrfn(levels(x), contrasts = contrasts) : unused argument (contrasts = contrasts) Even if we fix the missing argument: > contr.none <- function(n, ...) contrasts(factor(1:n), contrasts = FALSE) > contrasts(CO2$Treatment) <- "contr.none" > contrasts(CO2$Treatment) Error in 1:n : NA/NaN argument In addition: Warning messages: 1: In 1:n : numerical expression has 2 elements: only the first used 2: In factor(1:n) : NAs introduced by coercion What *did* work (inconsistently) was : > contrasts(CO2$Treatment) <- contr.none > contrasts(CO2$Treatment) 1 nonchilled 1 chilled 0 It no longer does in R-devel as 'contr.none' is now called with the factor *levels* (not nlevels) also in this case as documented. Note that the argument name 'n' in the default contrast functions such as contr.treatment() is a bit delicate as these support passing either levels or nlevels. Hope this helps. Best regards, Sebastian Meyer Am 30.06.22 um 00:27 schrieb Murray Efford: > This worked previously but gives an error in R-devel (Windows today), > triggering a warning to a package maintainer: > > contr.none <- function(n) contrasts(factor(1:n), contrasts = FALSE) > lm(uptake~Treatment, CO2, contrasts=list(Treatment=contr.none)) > > Error in 1:n : NA/NaN argument > In addition: Warning messages: > 1: In 1:n : numerical expression has 2 elements: only the first used > 2: In factor(1:n) : NAs introduced by coercion > > ______________________________________________ > R-devel@r-project.org mailing list > https://apc01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fstat.ethz.ch%2Fmailman%2Flistinfo%2Fr-devel&data=05%7C01%7Cmurray.efford%40otago.ac.nz%7Cad75da3bbad346a7d0c108da5a715362%7C0225efc578fe4928b1579ef24809e9ba%7C0%7C0%7C637921740057400452%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=vVBIv0EsP%2FmbohM9menUPmhfMl%2BsrLkohHA3JLu5BDc%3D&reserved=0 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel