R help - Jun 2002 - filter data frames

Hello!

I'm looking for an easy way to filter data frames.

Some rows in my data frame needs to be left out,
for instance, rows with invalid data.

Right now, if I want to pair two columns of this data frame,
I have to do this:
> pairs(as.data.frame(list(tstart=df$tstart[valid],tend=df$tend.sdr[valid])))
or this:
>
pairs(cbind(df$tstart,df$tend)[valid,],labels=c("tstart","tend"))
where 'valid' is a logical vector of valid rows.

Is there a way to filter a data frame without making a vector of
the columns, thus losing the column names?

Okay, perhaps I'm greedy. It's already working, what am I complaining
about? 

-- 
Christophe Weibel
_________________________
christophe.weibel at epfl.ch
Phone:    +41 21 312-3525
Prof:     +41 21 69-34244
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On Fri, 7 Jun 2002, Christophe Weibel wrote:
>
> Hello!
>
> I'm looking for an easy way to filter data frames.
>
> Some rows in my data frame needs to be left out,
> for instance, rows with invalid data.
>
> Right now, if I want to pair two columns of this data frame,
> I have to do this:
>
> >
pairs(as.data.frame(list(tstart=df$tstart[valid],tend=df$tend.sdr[valid])))
>
> or this:
>
> >
pairs(cbind(df$tstart,df$tend)[valid,],labels=c("tstart","tend"))
>
> where 'valid' is a logical vector of valid rows.
>
> Is there a way to filter a data frame without making a vector of
> the columns, thus losing the column names?
>
> Okay, perhaps I'm greedy. It's already working, what am I
complaining
> about?
What's wrong with df[valid, c("tstart","tend")], which
is what you appear
to want?

I am sure that's in the R Introduction.

-- 
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 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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