[R] Aggregation using list with Hmisc summarize function

[Gabor Grothendieck]

Note that you don't really need list or llist in this case:

summarize(x, by = mydata[2:3], FUN = mean, na.rm = TRUE)

Also you could use aggregate:

aggregate(mydata[1], mydata[2:3], mean, na.rm = TRUE)


On 12/28/06, Muenchen, Robert A (Bob) <muenchen at utk.edu> wrote:
> Hi All,
>
>
>
> I'm using the Hmisc summarize function and used list instead of llist to
> provide the by variables. It generated an error message. Is this a bug,
> or do I misunderstand how Hmisc works with lists? The program below
> demonstrates the error message.
>
>
>
> Thanks,
>
> Bob
>
>
>
> x<-1:8
>
> group <- c(1,1,1,1,2,2,2,2)
>
> gender<- c(1,2,1,2,1,2,1,2)
>
>
>
> mydata<-data.frame(x,group,gender)
>
> attach(mydata)
>
>
>
> # Creating a list using Hmisc llist works:
>
> summarize(x, by=llist(group,gender), FUN=mean, na.rm=TRUE)
>
>
>
> # Creating a list using built-in list function does not:
>
> summarize(x, by= list(group,gender), FUN=mean, na.rm=TRUE)
>
>
>
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