Hi Daniela,
There may be other more elegant ways of doing it, but here is one:
> myD <- data.frame(code = sample(3, 10, rep = T), prev = rnorm(10), Pr_mean =
> 0)
> myD
codeprev Pr_mean
1 3 -0.06710968 0
2 2 -1.43422034 0
3 1 0.22717580 0
4 3 0.32
Dear Daniela,
Try this:
set.seed(123)
myD<-data.frame(code=sample(letters[1:5],200,replace=T),value=rnorm(200))
tapply(myD$value,myD$code,mean)
a b c d e
0.04401465 0.07813648 0.07018791 -0.14508544 -0.02369875
See ?tapply for more information
Would ave() do what you want?
Rashid
On Tue, 8 Jul 2008, Daniela Ottaviani wrote:
> Dear All,
>
> I have a database of 200 observations named myD.
> In the dataframe there are a column named code (with codes varying from 1 to
> 77), a column named "prevalence" with some quantitative measur
On Tue, Jul 8, 2008 at 3:18 PM, Daniela Ottaviani <[EMAIL PROTECTED]> wrote:
> Dear All,
>
> I have a database of 200 observations named myD.
> In the dataframe there are a column named code (with codes varying from 1 to
> 77), a column named "prevalence" with some quantitative measurements are
>
On 08-Jul-08 13:18:13, Daniela Ottaviani wrote:
> Dear All,
> I have a database of 200 observations named myD.
> In the dataframe there are a column named code (with codes varying
> from 1 to 77), a column named "prevalence" with some quantitative
> measurements are given and an column named Pr_mea
[mailto:[EMAIL PROTECTED] On Behalf Of Daniela Ottaviani
> Sent: Tuesday, July 08, 2008 7:18 AM
> To: r-help@r-project.org
> Subject: [R] Question: Beginner stuck in a R cycle
>
> Dear All,
>
> I have a database of 200 observations named myD.
> In the dataframe there are a column
Dear All,
I have a database of 200 observations named myD.
In the dataframe there are a column named code (with codes varying from 1 to
77), a column named "prevalence" with some quantitative measurements are given
and an column named Pr_mean, with no values.
I would like to set a cycle to comp
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