[R] Selecting cases from a data frame

[Andrew Perrin]

Thanks to all who replied - the missing comma was, in fact, the issue.

ap

----------------------------------------------------------------------
Andrew J Perrin - andrew_perrin at unc.edu - http://www.unc.edu/~aperrin
 Assistant Professor of Sociology, U of North Carolina, Chapel Hill
      269 Hamilton Hall, CB#3210, Chapel Hill, NC 27599-3210 USA


On 19 Mar 2002, Peter Dalgaard BSA wrote:

> Andrew Perrin <andrew_perrin at unc.edu> writes:
> 
> > My apologies if this is obvious - I assume it is but still can't seem to
> > make it work.
> > 
> > I've got a data frame acps.df; I want to run an analysis on a subset of
> > that data frame, defined as the subset for which the value of OGMCAT (a
> > column in the data frame) is anything OTHER than 9, 11, or 12.  So I'd
> > like to define a new data frame that consists of the same variables as in
> > acps.df, but without those cases. I tried this:
> > 
> > > acps.nopg.df<-acps.df[(acps.df$OGMCAT != 9) & (acps.df$OGMCAT != 11) &
> > (acps.df$OGMCAT !=  12)]
> > 
> > but got this:
> > 
> > Error in "[.data.frame"(acps.df, (acps.df$OGMCAT != 9) & (acps.df$OGMCAT
> > !=  : 
> >         undefined columns selected
> > 
> > Thanks for any advice.
> 
> Looks like you need a comma in the indexing there. Indexing a data
> frame by a single index means that you are selecting columns, so you
> need two, the second one of which is empty.
> 
> BTW, this stuff is easier written as:
> 
> acps.nopg.df<-acps.df[acps.df$OGMCAT %in% c(9,11,12),]
> 
> 
> -- 
>    O__  ---- Peter Dalgaard             Blegdamsvej 3  
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
> 

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