On 2012-04-16 10:43, Michael Friendly wrote:
[Env: R 2.14.2 / Win Xp]In the script below, I want to select some variables from rrcov::OsloTransect, delete cases with any missing data, and subset the data frame Oslo to remove cases for two levels of the factor litho that occur with low frequency. The checks I run on my new data frame Oslo look OK, but I when I try to fit a multivariate linear model with lm(), I am getting an error: variable lengths differ (found for 'litho'). How can I fix this? > data(OsloTransect, package="rrcov") > # keep a subset of variables& rename some variables > Oslo<-OsloTransect[c("X.ID", "XCOO", "YCOO", "X.FOREST", "X.WEATHER", "X.FLITHO", "ALT")] > colnames(Oslo)<- c("site", "XC", "YC", "forest", "weather", "litho", "altitude") > Oslo<- cbind(Oslo, OsloTransect[,c("Cu", "Fe", "K", "Mg", "Mn", "P", "Zn")]) > # make site a factor > Oslo[,"site"]<- factor(Oslo[,"site"]) > > # log transform the chemical elements > Oslo[,8:14]<- log(Oslo[,8:14]) > > # delete cases with missing data > Oslo<- Oslo[complete.cases(Oslo),] > nrow(Oslo) [1] 350 > > # delete low frequency litho=="GNEID_O" | "MICSH" > Oslo<- subset(Oslo, !litho %in% c("GNEID_O", "MICSH"), drop=TRUE) > nrow(Oslo) [1] 332 > Oslo<- droplevels(Oslo) > table(Oslo$litho) CAMSED GNEIS_O GNEIS_R MAGM 98 89 32 113 > nrow(Oslo) [1] 332 > mod1<- lm(cbind("Cu", "Fe", "K", "Mg", "Mn", "P", "Zn") ~ litho + forest + weather, data=Oslo) Error in model.frame.default(formula = cbind("Cu", "Fe", "K", "Mg", "Mn", : variable lengths differ (found for 'litho') >
Michael, Unless I'm missing something, don't you just have to drop the quotes in your cbind()? Peter Ehlers ______________________________________________ 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.
