Hi Steven,
how about this (using simple matrix algebra)
wind<-5 #size of window to be aggregated
if (ncol(m)%%wind!=0) stop('dimension of m does not fit') #crude check
tmat<-apply(diag(ncol(m)/wind),1,function(x)rep(x,each=wind))/wind
m%*%tmat
hth.
Am 15.07.2010 11:39, schrieb steven mosher:
> Given a matrix of MxN
> want to take the means of rows in the following fashion
> m<-matrix(seq(1,80),ncol=20, nrow=4)
> result<-matrix(NA,nrow=4,ncol=20/5)
> result[,1]<-apply(m[,1:5],1,mean)
> result[,2]<-apply(m[,6:10],1,mean)
> result[,3]<-apply(m[,11:15],1,mean)
> result[,4]<-apply(m[,16:20],1,mean)
> result
> [,1] [,2] [,3] [,4]
> [1,] 9 29 49 69
> [2,] 10 30 50 70
> [3,] 11 31 51 71
> [4,] 12 32 52 72
>
> So, I want the mean of every successive 5 values in a row
>
> as the dimension in columns is wide I cant write it with multiple apply as
> above
>
> [[alternative HTML version deleted]]
>
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