[R] by group

[Jim Lemon]

Hi Val,
I think you answered your own question:

by(dat$wt,dat[,c("Sex","Year")],mean)

Jim

On Tue, Nov 2, 2021 at 8:09 AM Val <valkremk using gmail.com> wrote:
>
> Hi All,
>
> How can I generate mean by group. The sample data looks like as follow,
> dat<-read.table(text="Year Sex wt
> 2001 M 15
> 2001 M 14
> 2001 M 16
> 2001 F 12
> 2001 F 11
> 2001 F 13
> 2002 M 14
> 2002 M 18
> 2002 M 17
> 2002 F 11
> 2002 F 15
> 2002 F 14
> 2003 M 18
> 2003 M 13
> 2003 M 14
> 2003 F 15
> 2003 F 10
> 2003 F 11  ",header=TRUE)
>
> The desired  output  is,
>              M        F
> 2001    15        12
> 2002    16.33   13.33
> 2003    15          12
>
> Thank you,
>
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