[R] grouping

[Giovanni Petris]

Probably something along the following lines:

> x <- c(  46, 125 , 36 ,193, 209, 78, 66, 242 , 297 , 45)
> sorted <- c(36 , 45 , 46,  66, 78,  125,193, 209, 242, 297)
> tapply(sorted, INDEX = (seq_along(sorted) - 1) %/% 3, FUN = mean)
        0         1         2         3 
 42.33333  89.66667 214.66667 297.00000 

Hope this helps,
Giovanni

On Tue, 2012-04-03 at 08:47 -0400, Val wrote:
> Hi all,
> 
> Assume that I have the following 10 data points.
>  x=c(  46, 125 , 36 ,193, 209, 78, 66, 242 , 297 , 45)
> 
> sort x  and get the following
>   y= (36 , 45 , 46,  66, 78,  125,193, 209, 242, 297)
> 
> I want to  group the sorted  data point (y)  into  equal number of
> observation per group. In this case there will be three groups.  The first
> two groups  will have three observation  and the third will have four
> observations
> 
> group 1  = 34, 45, 46
> group 2  = 66, 78, 125
> group 3  = 193, 209, 242,297
> 
> Finally I want to calculate the group mean
> 
> group 1  =  42
> group 2  =  87
> group 3  =  234
> 
> Can anyone help me out?
> 
> In SAS I used to do it using proc rank.
> 
> thanks in advance
> 
> Val
> 
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> 
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-- 

Giovanni Petris  <GPetris at uark.edu>
Associate Professor
Department of Mathematical Sciences
University of Arkansas - Fayetteville, AR 72701
Ph: (479) 575-6324, 575-8630 (fax)
http://definetti.uark.edu/~gpetris/