Hi,
Try:
set.seed(25)
X<- matrix(sample(1:50,3*140,replace=TRUE),nrow=140)
#either
res1<-do.call(rbind,lapply(split(as.data.frame(X),((seq_len(nrow(X))-1)%/%10)+1),function(x)
apply(x,2,mean)))
#or
res2<-t(sapply(split(as.data.frame(X),((seq_len(nrow(X))-1)%/%10)+1),colMeans))
identical(res1,res2)
#[1] TRUE
#orlibrary(itertools)
it<-ihasNext(isplitRows(X,chunkSize=10))
while(hasNext(it)){
print( apply(nextElem(it),2,mean))
}
#[1] 23.4 29.1 31.5
#[1] 28.2 21.8 17.2
#[1] 14.3 24.3 36.4
#[1] 22.2 25.2 24.2
#[1] 28.5 22.6 27.3
#[1] 19.6 25.6 20.0
#[1] 25.7 16.3 27.9
#[1] 20.0 24.8 26.7
#[1] 26.3 30.0 33.0
#[1] 21.9 24.0 32.3
#[1] 25.6 27.2 34.4
#[1] 13.7 30.2 16.7
#[1] 23.2 27.0 25.3
#[1] 26.4 28.6 25.2
head(res1)
# V1 V2 V3
#1 23.4 29.1 31.5
#2 28.2 21.8 17.2
#3 14.3 24.3 36.4
#4 22.2 25.2 24.2
#5 28.5 22.6 27.3
#6 19.6 25.6 20.0
A.K.
Dear,
I have a matrix with 140 rows. With the following code, I can calculate the
mean of each column.
> X <- matrix
> apply(X,MARGIN=2,FUN=mean)
But, how to calculate the mean of each 10 rows?
Thank you at advance.
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