apply() will hit all the rows/columns at once so you don't need the loop construct at all.
E.g., x <- matrix(rnorm(20), ncol = 5) ## One Line y1 <- apply(x, 1, mean) ## Or Four y2 <- numeric(nrow(x)) for(i in 1:nrow(x)){ y2[i] <- mean(x[i,]) } ## But they're the same identical(y1, y2) # TRUE Does that clarify things? Michael On Thu, Mar 29, 2012 at 12:25 PM, Christopher Kelvin <chris_kelvin2...@yahoo.com> wrote: > Please, can you be a little specific for me about where to inside your > suggestion to make the code complete complete. I have tried it but i am > getting errors. > Thank you > Chris Kelvin > > > ----- Original Message ----- > From: R. Michael Weylandt <michael.weyla...@gmail.com> > To: Christopher Kelvin <chris_kelvin2...@yahoo.com> > Cc: "r-help@r-project.org" <r-help@r-project.org> > Sent: Thursday, March 29, 2012 11:33 PM > Subject: Re: [R] matrix with Loop > > apply(x, 1, mean) > apply(x, 2, median) > > or for more speed rowMeans() > > ? apply > > Michael > > On Thu, Mar 29, 2012 at 9:00 AM, Christopher Kelvin > <chris_kelvin2...@yahoo.com> wrote: >> Hello! >> I got something to ask..whether you can help me with the R program...i got >> this for example 5x4 matrix..and i want to find: >> i) mean for each row of the matrix >> ii) median for each column of the matrix >> and i need to do this using a loop function...below is my program..u try to >> check it for me as the output that i got is not what i desired...thanks.. >> >> data<-rnorm(20,0,1) >> dim(data)<-c(5,4) >> is.matrix(data) >> data >> a<-function(x) >> { >> for(i in 1:nrow(x)) >> { >> for(j in 1:ncol(x)) >> { >> med<-median(x[,j]) >> mean<-mean(x[i,]) >> print(c(med=med,mean=mean)) >> } >> } >> } >> a(data) >> >> Chris Guure >> Researcher >> Institute for Mathematical Research >> UPM >> >> ______________________________________________ >> R-help@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. > ______________________________________________ R-help@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.