try this:
DF.lis <- list(
one = data.frame(x = c(1,2,3), y = c(1,2,2), z = c(3,1,1)),
two = data.frame(x = c(2,5,2), y = c(2,3,1), z = c(4,1,2))
)
Reduce("+", DF.lis) / length(DF.lis)
I hope it helps.
Best,
Dimitris
On 11/24/2010 8:37 PM, Tim Howard wrote:
R users,
This probably involves a simple incantation of one of the flavors of apply...
that I can't yet figure out. Consider a list of data frames. I'd like to apply
a function (mean) across the list and return a dataframe of the same dimensions
where each cell represents the mean of that cell across all dataframes.
# set up the list
x<- vector("list",2)
names(x)<- c("one","two")
# add data to the list
for(i in 1:2){
y = i^2
x[[i]]<-
data.frame("a"=c(y,2*y,3*y),"b"=c(y+1,y+2,y+3),"c"=c(2*y+1,2*y+2,2*y+3))
}
#show the list
x
$one
a b c
1 1 2 3
2 2 3 4
3 3 4 5
$two
a b c
1 4 5 9
2 8 6 10
3 12 7 11
#the result should be
a b c
1 2.5 3.5 6
2 5 4.5 7
3 7.5 5.5 8
Can anyone direct me down the right path?
Thanks in advance
Tim Howard
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--
Dimitris Rizopoulos
Assistant Professor
Department of Biostatistics
Erasmus University Medical Center
Address: PO Box 2040, 3000 CA Rotterdam, the Netherlands
Tel: +31/(0)10/7043478
Fax: +31/(0)10/7043014
Web: http://www.erasmusmc.nl/biostatistiek/
______________________________________________
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and provide commented, minimal, self-contained, reproducible code.
