Re: [R] question about subseting a dataframe

From: Charles Plessy <charles-listes-r_at_plessy.org>
Date: Sat, 10 May 2008 12:36:47 +0900

Le Fri, May 09, 2008 at 11:23:37PM -0400, Dipankar Basu a écrit :
> > ex <- data.frame(id=id,year=year,x=x)
> > ex1 <- subset(ex[which(ex$id=="A"|ex$id=="B"),])
> > tapply(ex1$x, ex1$id, mean)
> A B C
> 22.5 32.5 NA

Dear Dipankar,

The reason for this behaviour is that the class of ex$id is "factor". You can avoid this by using the I command, like in:

ex <- data.frame(id=I(id),year=year,x=x)

Have a nice day,

-- 
Charles Plessy
http://charles.plessy.org
Wakō, Saitama, Japan

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Received on Sat 10 May 2008 - 03:50:48 GMT

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