Dear expeRts, I came across the following error in using model.frame:
# make a data.frame jet=data.frame(y=rnorm(10),x1=rnorm(10),x2=rnorm(10),rvar=rnorm(10)) # spec of formula mf1=y~x1+x2 # make the model.frame mf=model.frame(formula=mf1,data=jet,weights=rvar) Which gives the desired output: > mf y x1 x2 (weights) 1 0.8041254 0.1815366 0.4999551 1.4957814 2 -0.2546224 1.9368141 -2.2373186 0.7579341 3 0.8627935 -0.6690416 1.3948077 -0.2107092 4 0.3951245 0.5733776 -1.2926074 -0.3289226 5 -1.4805766 -0.6113256 1.1635959 0.2300376 6 -0.7418800 -0.1610305 0.4057340 -0.2280754 7 -1.1420962 -0.9363492 -0.4811192 -0.9258711 8 0.3507427 1.8744646 1.3227931 0.5292313 9 1.4196519 0.1340283 -1.3970614 -0.7189726 10 -1.0164708 -0.2044681 -0.6825873 -0.1719102 However, doing this inside another function like this: makemodelframe <- function(formula,data,weights) { mf=model.frame(formula=formula,data=data,weights=weights) mf } produces the following error: > makemodelframe(mf1,jet,weights=rvar) Error in model.frame(formula, rownames, variables, varnames, extras, extranames, : invalid variable type Searching the R-help archives I came across bug-reports about this but couldn't figure out whehter the bug was solved or whether there are work-arounds available. platform: platform powerpc-apple-darwin7.9.0 arch powerpc os darwin7.9.0 system powerpc, darwin7.9.0 status major 2 minor 2.1 year 2005 month 12 day 20 svn rev 36812 language R Any hints are welcome, Best, Ingmar ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html