While we wait for others to provide the best way, here's one way (if I understand your question correctly):
numrows <- 10 x <- rnorm(25 * numrows) dat <- as.data.frame(matrix(x, nc = 25)) newdat <- as.data.frame(matrix(0, nr = numrows, nc = 14)) for(j in 1:14) newdat[, j] <- rowMeans(dat[, j:(j + 11)], na.rm = TRUE) Peter Ehlers r user wrote: > I have a dataframe of 25 columns and 100,000 rows > called “testdf”. > > I wish to build a new dataframe, with 14 columns and > 100,000 rows. > > I wish the new dataframe to have the “trailing 12 > column” mean. That is, I want column 1 of the new > dataframe to have soemthing like: > > “( mean(testdf[,1:12],na.rm=T)” > > What is the best way to accomplish this? > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
