[R] Is the aggregate function the best way to do this?

[Bert Jacobs]

Hi Mohamed,
Thx for the answer.
And what should I do if my fun function is not 'sum' but 'max'?
Bert
-----Original Message-----
From: Mohamed Lajnef [mailto:Mohamed.lajnef at inserm.fr] 
Sent: 17 February 2010 10:02
To: Bert Jacobs
Cc: r-help at r-project.org
Subject: Re: [R] Is the aggregate function the best way to do this?

Hi Bret,

Try to use rowSums function

Regrads
M

Bert Jacobs a écrit :
> Hi,
>
>  
>
> I'm having a dataframe 'Subset1' with a number of factor variables and 160
> numerical variables
>
> Now I want to make sums for all rows that have the same values for the
> different factor variables, except for the factor variables:
VAR1,VAR2,VAR3
> who may have the same values.
>
> With the formula given below this works great, but in a situation with
15000
> rows and 13 factor variables the calculation takes more than 2 minutes. 
>
> So my question is: Does anyone knows if there exists a faster alternative?

>
>  
>
> Subset1.AGG <-
> as.data.frame(aggregate(Subset1[,(ncol(Subset1)-159):ncol(Subset1)],
> list(VAR1 = Subset1$VAR1,VAR2=Subset1$VAR2,VAR3 = Subset1$VAR3), FUN=sum)
)
>
>  
>
> Thank you very much for helping me out,
>
> Bert
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
>
>   


-- 


Mohamed Lajnef,IE 
INSERM U955 eq 15
Pôle de Psychiatrie
Hôpital CHENEVIER
40, rue Mesly
94010 CRETEIL Cedex FRANCE
Mohamed.lajnef at inserm.fr
tel : 01 49 81 31 31 (poste 18470)
Sec : 01 49 81 32 90
fax : 01 49 81 30 99