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Re: group by

To: "'Wensui Liu'" <liuwensui@gmail.com>, "'Neung-Hwan Oh'" <ultisol@gmail.com>
Subject: Re: group by
From: <Rich@Mango-Solutions.com>
Date: Wed, 14 Mar 2007 21:17:52 -0000
Cc: <s-news@wubios.wustl.edu>
In-reply-to: <20070314211413.E237E137456@mailgate.biostat.wustl.edu>
Thread-index: AcdmfHsQ62HCMIqaSVaejE3K2AyILgAAPlaQAAAiB9A=
Sorry ...

I mean "aggregate(df$value, df[,1:3], mean)"

Rich.
mangosolutions

-----Original Message-----
From: Rich@Mango-Solutions.com [mailto:Rich@Mango-Solutions.com] 
Sent: 14 March 2007 21:14
To: 'Wensui Liu'; 'Neung-Hwan Oh'
Cc: s-news@wubios.wustl.edu
Subject: Re: [S] group by

Yes ... you can use tapply in S.  For the structure you're using, I'd
probably recommend "aggregate" though ...

Something like "aggregate(df[,1:3], df$value, mean)"

Rich.
mangosolutions

-----Original Message-----
From: Wensui Liu [mailto:liuwensui@gmail.com] 
Sent: 14 March 2007 21:02
To: Neung-Hwan Oh
Cc: s-news@wubios.wustl.edu
Subject: Re: [S] group by

I am not sure if in Splus, there is a nice function like tapply() in R or
not.

On 3/14/07, Neung-Hwan Oh <ultisol@gmail.com> wrote:
> Hello,
>
> How can you calculate the following example in s-plus?   In Access, it is
> relatively easy with "Group By" and I am wondering whether there is a
> similar function that I missed in S-Plus.
>
>
>
> "From this table"
>
> site.no date time value
>
> 1 1989/04/27 12:00   1.0
>
> 2 1975/10/01 19:00   2.0
>
> 2 1975/10/01 20:00   4.0
>
> 3 1993/04/10 09:00   3.0
>
> 3 1993/04/10 12:00   6.0
>
> 3 1993/04/10 15:00   9.0
>
>
>
> "To this (averages per date per site)" + (count column?)
>
> 1 1989/04/27 12:00 1.0  (1.0)
>
> 2 1975/10/01 19:30 3.0  (2.0)
>
> 3 1993/04/10 12:00 6.0  (3.0)
>
>
>
> Many thanks!
>
> NH


-- 
WenSui Liu
A lousy statistician who happens to know a little programming
(http://spaces.msn.com/statcompute/blog)
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