subsetting a dataframe
On Tue, 4 Mar 2008, John Sorkin wrote:
windows XP
R 2.6.0
I am having problems deleting a row from a data frame. I create my dataframe by subsetting a larger dataframe:
ShortLavin<-Lavin[Lavin[,"Site"]=="PP" | Lavin[,"Site"]=="CC" | Lavin[,"Site"]=="FH",]
I then perform a glm using the data frame and plot the results.
fit1poisson<-glm(NumUniqOpPt~Seq+Site,family=poisson(link = "log"),data=ShortLavin,offset=log(NumUniqPt))
plot(fit1poisson)
On the plots I see a point labeled as 127 that is an extreme value. I want to re-run the glm excluding the extreme observation. I have tried several methods to exclude the observation (shown below), none have worked.
Minus127<-ShortLavin[-127,]
Minus127<-ShortLavin[-"127",]
Minus127<-ShortLavin[-c(127),]
Minus127<-ShortLavin[-c("127"),]
None of these worked. Suggestions on how I can remove observation 127 would be appreciated
Assuming this is row name "127" derived from row 127 of the original
dataset,
Minus127 <- ShortLavin[-match("127", row.names(ShortLavin)), ]
Thank you, John John Sorkin M.D., Ph.D. Chief, Biostatistics and Informatics University of Maryland School of Medicine Division of Gerontology Baltimore VA Medical Center 10 North Greene Street GRECC (BT/18/GR) Baltimore, MD 21201-1524 (Phone) 410-605-7119 (Fax) 410-605-7913 (Please call phone number above prior to faxing)
Brian D. Ripley, ripley at stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595