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

Bert Jacobs bert.jacobs at figurestofacts.be
Wed Feb 17 10:10:39 CET 2010


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]]
>
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-- 


Mohamed Lajnef,IE 
INSERM U955 eq 15
Pôle de Psychiatrie
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40, rue Mesly
94010 CRETEIL Cedex FRANCE
Mohamed.lajnef at inserm.fr
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