Kang Tu is right and you will certainly need to learn the techniques being
suggesting to do more advanced data analysis, but it sounds like for your
immediate problem the following might work:

# Suppose df is your data frame
rowSums(df[,4:27])

This takes a sub-data-frame consisting only of columns 4 through 27 and does
rowSums on them.

Hope this helps,

Michael Weylandt

On Sun, Sep 4, 2011 at 7:16 PM, Kang Tu <kang.tu.rfan@gmail.com> wrote:

> Would you mind show us a simple example of your data? It is hard to
> understand your request directly from your text.
>
> If you just want to combine the data, you can try cbind() function
> directly, or you can use subset() function to get a subset of your
> data.frame. If you want to selectively aggregate some statistics you can
> try aggregate() function. If you want a more complex aggregation, you
> may want to try ddply() in 'plyr' package.
>
> On Sun, 2011-09-04 at 15:25 -0700, joonsum wrote:
> > First time using R and have so many basic questions.
> >
> > The problem that I have confronted is combining rows. I have a data frame
> > that contains daily rain falls from 60 to 80. There are 27 columns which
> are
> > Year,month, day, and record in hours.
> >
> > I am trying to combine the 4th column to the 27th to get daily rain fall
> > data.
> > rowSums() works in the case of merging all rows but in my case, I need to
> be
> > selective. How should I start?
> >
> >
> > --
> > View this message in context:
> http://r.789695.n4.nabble.com/combining-rows-tp3790068p3790068.html
> > Sent from the R help mailing list archive at Nabble.com.
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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