[R] Mean calculation of groups

[Bert Gunter]

Nico:

1. Thanks for the example.

2. Please read -- or at least peruse -- the tutorial, An Introduction
to R (or other tutorial that you might find on the Web, there are
many) to familiarize yourself with R's features.

3. This is an example of what the apply() family of functions can do,
so you might want to find out about that (Google is your friend here).
?lapply would get you started with R's Help, but that's rather dense.

4. You may also want to look at the plyr package which has organized
and standardized in a convenient way much of the disparate
functionality of the apply-type functions.

5. Finally, to answer your question, ?ave.

Cheers,
Bert

On Tue, Sep 25, 2012 at 7:37 AM, Nico Met <nicomet80 at gmail.com> wrote:
> Dear all,
>
> I have a data frame and I want to calculate mean of the first column which
> is same name for example: CTK100 group
>
>> dput(test)
> structure(list(Name = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 3L,
> 3L, 3L, 3L, 3L, 3L, 3L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
> 2L), .Label = c("CTK100", "CTK103", "CTK121"), class = "factor"),
>     Score = c(236.9726, 207.0055, 237.3464, 224.4774, 236.5034,
>     206.7382, 233.94, 240.31, 240.9, 235.15, 223.36, 248.67,
>     249.25, 201.4051, 244.1689, 182.2756, 229.001, 241.3211,
>     196.0453, 232.6055, 225.0783, 196.0453, 232.6055, 225.0783
>     )), .Names = c("Name", "Score"), class = "data.frame", row.names =
> c(NA,
> 24L))
>
>
> How can write as a programme? because the original file has more than 60K
> names with duplicates.
>
>
> Many thanks
>
> Nico
>
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>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

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Phone: 467-7374
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