[R] Counting within groups / means by groups

[Jeff Newmiller]

Help file ?ave should apply here.

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Sent from my phone. Please excuse my brevity.

On November 10, 2014 6:39:47 AM PST, David Studer <studerov at gmail.com> wrote:
>Hi everyone!
>
>I have problems finding a solution to the following two problems:
>
>My sample-dataframe consists of two variables "group" and "value":
>
>group<-c("A", "A", "A", "B", "B", "B", "B", "C")
>value<-c(1,3,2,2,2,4,4,1)
>df<-as.data.frame(cbind(group, value))
>
>Problem 1:
>**********
>
>Now I'd like to count the number of group-A-cases, group-B-cases etc
>and
>write
>this number into a new column. It should be like:
>
>count_group<-c(3, 3, 3, 4, 4, 4, 4, 1)
>
>Problem 2:
>***********
>
>I'd like to add new column with the mean values (or any other function)
>within
>my groups. E.g:
>
>Group A: (1+3+2)/3=2
>Group B: (2+2+4+4)/4=3
>Group C: =1
>
>Now I'd add another column 2 2 3 3 3 3 1
>
>
>Can anyone help me, how this can be done best?
>
>Thank you!
>David
>
>	[[alternative HTML version deleted]]
>
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