[R] subsetting a dataframe

From: John Sorkin <jsorkin_at_grecc.umaryland.edu>
Date: Tue, 04 Mar 2008 08:41:02 -0500


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

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)

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