Hi
And if you are reading tapply help page, you can also notice
?aggregate
which maybe could suit better.
Cheers
Petr
> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Bert
> Gunter
> Sent: Tuesday, June 21, 2016 7:18 AM
> To: Paolo Letizia <paolo.letizia at gmail.com>
> Cc: R Help <r-help at r-project.org>
> Subject: Re: [R] Data aggregation
>
> ?tapply
>
> You should have encountered this already in most basic R tutorials.
> Have you gone through any? If not, you should. In particular,you need to
> learn about R's basic data structures (e.g. data frames).
>
> Alternatively, the dplyr package has many elegant tools for this sort of
thing.
> You might do well to learn it instead or in addition to the *apply type
> operations of base R.
>
> Finally, I should ask: is this homework? This list tries to implement a no
> homework policy.
>
> Cheers,
> Bert
>
>
> Bert Gunter
>
> "The trouble with having an open mind is that people keep coming along
and
> sticking things into it."
> -- Opus (aka Berkeley Breathed in his "Bloom County" comic strip
)
>
>
> On Mon, Jun 20, 2016 at 2:34 PM, Paolo Letizia <paolo.letizia at
gmail.com>
> wrote:
> > Dear All:
> > I have a data frame with 3 columns: "Regime",
"Industry", and "Cost".
> > I want to sum the value of "Cost" for each industry and
"Regime".
> > Example:
> >
> > The data frame is:
> > Regime, Industry, Cost
> > 10, 01, 370
> > 11, 01, 400
> > 10, 02, 200
> > 10, 01, 500
> > 11, 02, 60
> > 10, 02, 30
> >
> > I want the following output:
> > 01, 10, 870
> > 01, 11, 400
> > 02, 10, 230
> > 02, 11, 600
> >
> > Can you please help me on this? Paolo
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > 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 at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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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