[R] Subset function

[William Dunlap]

I thought that the main advantage of subset() over [()
is that you only mention the name of the data.frame once,
in the first argument, not in the second:
  > x <- data.frame(xin=c(1, 8, 16, 1, 8, 16), xout=c(14, 5, 884, 14, 5, 884))
  > subset(x, xin > 7, select = xout) # not x$xin > 7
    xout
  2    5
  3  884
  5    5
  6  884

A secondary advantage of subset is that treats NA's in
the subset= argument the same as FALSE's.

I think subset is handy for one-off usage, but in general
purpose functions the [ function is better: it uses standard
argument evaluation and is faster.

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Rainer
> Schuermann
> Sent: Friday, September 09, 2011 5:44 AM
> To: r-help at r-project.org; stat.kk
> Subject: Re: [R] Subset function
> 
> Does that help:
> 
> > x
>       xin     xout
> 1       1       14
> 2       8        5
> 3      16      884
> 4       1       14
> 5       8        5
> 6      16      884
> 
> > subset( x, x$xin > 7, select = xout )
>       xout
> 2        5
> 3      884
> 5        5
> 6      884
> 
> Rgds,
> Rainer
> 
> 
> On Friday 09 September 2011 04:38:44 stat.kk wrote:
> > Hi,
> >
> > can anyone help me how to use 'subset' function on my data frame?
> > I have created data frame 'data' with a few variables and with row names.
> > Now I would like to subset rows with concrete row names.
> > Using data[] I know how to do it. But I dont know how to formulate the
> > subset condition:
> > subset(data, subset = ?, select = c(var1, var2))
> >
> > Thank you very much,
> > stat.kk
> >
> > --
> > View this message in context:
> > http://r.789695.n4.nabble.com/Subset-function-tp3801397p3801397.html Sent
> > from the R help mailing list archive at Nabble.com.
> >
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