[R] all data frame columns SUBSET

[Hamid Hamid]

Dear All,
I have a data frame (mydata), with let say 5 columns V1,V2,...,V5.
(we know the power set of {V1,V2,..,V5} has  2^5-1 elements). I need
to construct a vector T of length 5 which its i-th element is  the
maximum of (let say) mean values obtained based on the columns subset
of size i. (MY FUNCTION TO APPLY ON COLUMNS SUBSET IS NOT SO SIMPLE AS
MEAN AND  I WILL REPLACE IT.)

I mean:

T[1]=max(mean(mydata[,1]),...,mean(mydata[,5]))
T[2]=max(mean(mydata[,c(1,2)],mean(mydata[,c(1,3)],...,mean(mydata[,c(1,5])
T[3]=max(mean(mydata[,c(1,2,3)],mean(mydata[,c(1,2,4)],...,mean(mydata[,c(3,4,5)])
....
T[5]=max(mean(mydata[,c(1,2,3,4,5)]

Many thanks in advance.

Hamid