Re: [R] Calculate of data frame

From: Zhang, Fan <fzhang_at_doubleclick.net>
Date: Fri 15 Jul 2005 - 04:26:38 EST


Thanks for your answer, Peter. Now I have a new data frame which is sorted by (model,date) pair. Since the sorting is done to charactors, I have 7/1/2005 followed by 7/10/2005 instead of 7/2/2005. How can I do the aggregation and at the same time, make the result sorted the way I want (i.e, 7/1/2005 followd by 7/2/2005)?

Thanks,

Fan
-----Original Message-----
From: pd@pubhealth.ku.dk [mailto:pd@pubhealth.ku.dk] On Behalf Of Peter Dalgaard Sent: Thursday, July 14, 2005 1:29 PM
To: Zhang, Fan
Cc: r-help@stat.math.ethz.ch
Subject: Re: [R] Calculate of data frame

"Zhang, Fan" <fzhang@doubleclick.net> writes:

> Now I want to get the total count and value for each model/date pair,
> like
> model count value date
> A 6 31.8 7/1/2005
> A 3 10.2 7/2/2005
> B 7 14.2 7/1/2005
> B 10 67.4 7/2/2005
>
> Anyone can tell me how to do this?

> aggregate(df[,c("count","value")],df[,c("date","model")],sum)

      date model count value
1 7/1/2005     A     6  31.8
2 7/2/2005     A     3  10.2
3 7/1/2005     B     7  14.2
4 7/2/2005     B    10  71.4


-- 
   O__  ---- Peter Dalgaard             ุster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)                  FAX: (+45) 35327907

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