[R] Average calculations

Jose Iparraguirre Jose.Iparraguirre at ageuk.org.uk
Wed Jan 23 14:32:24 CET 2013

Hi Nico,

You can use tapply:

> tapply( x[["Values" ]], x[[ "Names" ]], mean )
CK113234 CK113298 CK114042 CK116292 CK116296 
216.5061 190.1725 222.8710 220.4324 204.5741 


> tapply( x$Values, x$Names, mean )
CK113234 CK113298 CK114042 CK116292 CK116296 
216.5061 190.1725 222.8710 220.4324 204.5741

Hope it helps.


José Iparraguirre
Chief Economist
Age UK

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Nico Met
Sent: 23 January 2013 13:04
To: R help
Subject: [R] Average calculations

Dear all,

I have a matrix with two columns: "Names" and "Values"

In names: there are 4 groups they are, CK113234, CK116296, CK116292 and

I want to *sort values* (decreasing order) based on each group and
take average of the *top two numbers* in each of the groups.

> dput(x)
structure(list(Names = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 5L, 5L, 5L, 5L, 2L, 2L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 3L,
3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("CK113234", "CK113298",
"CK114042", "CK116292", "CK116296"), class = "factor"), Values =
223.29665, 221.63255, 211.29735, 217.75112, 210.97916, 222.67365,
216.0822, 189.83685, 194.1595, 210.66298, 223.637183333333, 187.74864,
192.5964, 237.593625, 216.8277, 225.8966, 228.00374, 214.99454,
211.38114, 218.7659, 209.9958, 214.804133333333, 215.184489473684,
224.2446, 217.559878571429, 232.022291666667, 214.02384, 236.393875,
228.73522)), .Names = c("Names", "Values"), class = "data.frame", row.names
= c(NA,

The out put will look like following:

 Names Values  CK113234 222,98  CK116296 217,14  CK116292 232,79  CK114042
Your help is appreciated.



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