Hi Jim,
Here is a suggestion using aggregate():
res <- with(df, aggregate(Angle, list(Trial, Treatment), mean, na.rm =
TRUE))
colnames(res) <- c('Trial','Treatment', 'Average_Angle')
res
# Trial Treatment Average_Angle
# 1 1 C 52.7455
# 2 2 C 81.7599
# 3 3 C 76.3234
# 4 1 U 62.5118
# 5 2 U 81.5520
HTH,
Jorge
On Thu, Nov 5, 2009 at 8:53 PM, jimdare <> wrote:
>
> Hi,
>
> I am create a new DF that summarizes the mean angle per treatment/trial, of
> the original DF (see below). I have had some success using:
> (tapply(df$Angle, INDEX=interaction(df$State,
> df$Trial), FUN=mean)); however, this gives the answer as a list, which
> means I would have to split the name to get the categories back. Does
> anyone know a simple way to transform the Original DF into Summary DF?
>
> Thanks in advance,
>
> James
>
>
> Original DF
>
> > df
> Angle Trial Treatment
> 1 43.1297 1 C
> 2 62.3613 1 C
> 3 88.2767 2 C
> 4 75.2431 2 C
> 5 91.3668 3 C
> 6 61.2800 3 C
> 7 55.5575 1 U
> 8 69.4661 1 U
> 9 67.5512 2 U
> 10 95.5528 2 U
> 11 75.8689 3 U
> 12 66.9070 3 U
>
> Summary DF
>
> > sdf
>
> Angle Trial Treatment
> 1 52.7455 1 C
> 2 ... 2 C
> 3 ... 3 C
> 4 ... 1 U
> 5 ... 2 U
> 6 ... 3 U
>
> --
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>
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