[R] How to use tapply with more than one variables grouped

[PIKAL Petr]

Hi

> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of noobmin
> Sent: Monday, October 22, 2012 2:28 AM
> To: r-help at r-project.org
> Subject: [R] How to use tapply with more than one variables grouped
> 
> I'm studying alone the R language for data preparation. I found a
> course at MIT for data preparation that uses python but I'm using R to
> learning. The first exercise is the preparation of data from a database
> that shows the contributions made to candidates for U.S. president. The
> database is described in FORMART
> ftp://ftp.fec.gov/FEC/Presidential_Map/2012/DATA_DICTIONARIES/CONTRIBUT
> OR_FORMAT.txt
> link. I wonder how to print the table showing how many states are
> President Obama the top candidate (by full amount of donations
> received) with R language?
> 
> I try using tapply method but, i dont understand how to working with
> more than one variable grouped. Could anyone help me in advance of the
> studies?
> 
How did you use tapply? Did you read help page? It points to ?aggregate which is maybe what you are looking for.

Regards
Petr

> 
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