Got it. Thanks so much.
Hannah
2012/8/16 arun <smartpink...@yahoo.com>
> Hi,
> Try this:
> dat1<-read.table(text="
> no. values ind sample
> 1 0.03325 1 1
> 2 0.03305 1 1
> 3 0.03185 1 1
> 4 0.03515 1 1
>
> -------------------------
> -------------------------
> 42 0.01085 5 2
> 43 0.01660 5 3
> 44 0.03060 5 4
> 45 0.06605 5 5
> ",sep="",header=TRUE)
> dat2<-within(dat1,{sample<-as.factor(sample)})
> ddply(dat2,.(sample), function(x) mean(x$values))
> # sample V1
> #1 1 0.033556
> #2 2 0.011120
> #3 3 0.017750
> #4 4 0.030220
> #5 5 0.062060
> A.K.
>
> ----- Original Message -----
> From: li li <hannah....@gmail.com>
> To: r-help <r-help@r-project.org>
> Cc:
> Sent: Thursday, August 16, 2012 9:31 PM
> Subject: [R] Apply a function according to factor levels.
>
> Dear all,
> I have a question on applying a function to the data according to factor
> levels.
> For example, for the data below, what is the best way to apply a function
> to
> "values" according to different levels of "samples" (1,2,3,4,5)?
> values ind sample
> 1 0.03325 1 1
> 2 0.03305 1 1
> 3 0.03185 1 1
> 4 0.03515 1 1
> 5 0.03375 1 1
> 6 0.01180 1 2
> 7 0.01850 1 3
> 8 0.02915 1 4
> 9 0.06200 1 5
> 10 0.03230 2 1
> 11 0.03345 2 1
> 12 0.03385 2 1
> 13 0.03605 2 1
> 14 0.03225 2 1
> 15 0.01145 2 2
> 16 0.01805 2 3
> 17 0.02950 2 4
> 18 0.05995 2 5
> 19 0.03425 3 1
> 20 0.03575 3 1
> 21 0.03535 3 1
> 22 0.03380 3 1
> 23 0.03410 3 1
> 24 0.01050 3 2
> 25 0.01735 3 3
> 26 0.03140 3 4
> 27 0.06170 3 5
> 28 0.03430 4 1
> 29 0.03185 4 1
> 30 0.03165 4 1
> 31 0.03380 4 1
> 32 0.03235 4 1
> 33 0.01100 4 2
> 34 0.01825 4 3
> 35 0.03045 4 4
> 36 0.06060 4 5
> 37 0.03280 5 1
> 38 0.03350 5 1
> 39 0.03215 5 1
> 40 0.03545 5 1
> 41 0.03285 5 1
> 42 0.01085 5 2
> 43 0.01660 5 3
> 44 0.03060 5 4
> 45 0.06605 5 5
>
>
> Thank you.
> Hannah
>
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>
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> PLEASE do read the posting guide
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>
>
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