Hi all,
I'm just having trouble getting row means of a matrix which
contain zero.
For example.
m=matrix(c(1:4, c(0, 0, 0, 0), c(1, 0, 1, 1)), nc=4, byrow=TRUE)
I want to be able to calculate means for non-zero elements for each row.
## what i have is this
apply((m[apply(m != 0, MARGIN=1, any),]), 1, mean)
## which returns
[1] 2.50 0.75
### what i want to get returned is this
[1] 2.50 *1
*meaning that the last row calculated the mean ignoring the zero. Anyone
got any ideas?
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On Aug 17, 2012, at 8:28 PM, Yingwei Lee wrote:> m=matrix(c(1:4, c(0, 0, 0, 0), c(1, 0, 1, 1)), nc=4, byrow=TRUE)is.na(m) <- m==0 rowMeans(m, na.rm=T) #[1] 2.5 NaN 1.0 -- David Winsemius, MD Alameda, CA, USA
On 18-08-2012, at 05:28, Yingwei Lee wrote:> Hi all, > I'm just having trouble getting row means of a matrix which > contain zero. > For example. > > m=matrix(c(1:4, c(0, 0, 0, 0), c(1, 0, 1, 1)), nc=4, byrow=TRUE) > > I want to be able to calculate means for non-zero elements for each row. > > ## what i have is this > apply((m[apply(m != 0, MARGIN=1, any),]), 1, mean) > ## which returns > [1] 2.50 0.75 > > ### what i want to get returned is this > [1] 2.50 *1 > > *meaning that the last row calculated the mean ignoring the zero. Anyone > got any ideas?Define function to compute mean of non zero elements f <- function(x) {k <- which(x!=0); mean(x[k])} then use apply apply(A,1,f) [1] 2.5 NaN 1.0 and to remove the NaN you could do z <- apply(A,1,f) z[!is.na(z)] or z[is.finite(z)] Berend
HI, Try this: ?m[m==0]<-NA apply(m,1,mean,na.rm=T) #[1] 2.5 NaN 1.0 A.K. ----- Original Message ----- From: Yingwei Lee <dingayinga at gmail.com> To: r-help at r-project.org Cc: Sent: Friday, August 17, 2012 11:28 PM Subject: [R] Row means of matrix. Hi all, ? ? ? ? ? I'm just having trouble getting row means of a matrix which contain zero. For example. m=matrix(c(1:4, c(0, 0, 0, 0), c(1, 0, 1, 1)), nc=4, byrow=TRUE) I want to be able to calculate means for non-zero elements for each row. ## what i have is this apply((m[apply(m != 0, MARGIN=1, any),]), 1, mean) ## which returns [1]? 2.50? 0.75 ### what i want to get returned is this [1] 2.50? *1 *meaning that the last row calculated the mean ignoring the zero. Anyone got any ideas? ??? [[alternative HTML version deleted]] ______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.