On 9/24/2008 10:38 AM, Marc Schwartz wrote: > on 09/24/2008 09:06 AM Doran, Harold wrote: >> Say I have the following data: >> >> testDat <- data.frame(A = c(1,NA,3), B = c(NA, NA, 3)) >> >>> testDat >> A B >> 1 1 NA >> 2 NA NA >> 3 3 3 >> >> rowsums() with na.rm=TRUE generates the following, which is not desired: >> >>> rowSums(testDat[, c('A', 'B')], na.rm=T) >> [1] 1 0 6 >> >> rowsums() with na.rm=F generates the following, which is also not >> desired: >> >> >>> rowSums(testDat[, c('A', 'B')], na.rm=F) >> [1] NA NA 6 >> >> I see why this occurs, but what I hope to have returned would be: >> [1] 1 NA 6 >> >> To get what I want I could do the following, but normally my ideas are >> bad ideas and there are codified and proper ways to do things. >> >> rr <- numeric(nrow(testDat)) >> for(i in 1:nrow(testDat)) rr[i] <- if(all(is.na(testDat[i,]))) NA else >> sum(testDat[i,], na.rm=T) >> >>> rr >> [1] 1 NA 6 >> >> Is there a "proper" way to do this? In my real data, nrow is over >> 100,000 >> >> Thanks, >> Harold > > The behavior you observe is documented in ?rowSums in the Value section: > > If there are no values in a range to be summed over (after removing > missing values with na.rm = TRUE), that component of the output is set > to 0 (*Sums) or NA (*Means), consistent with sum and mean.
Based on the difference in behavior for Sums and Means, this might be another possibility: rowMeans(testDat, na.rm=TRUE) * rowSums(!is.na(testDat)) [1] 1 NA 6 > So: > >> sum(c(NA, NA), na.rm = TRUE) > [1] 0 > > > As per the definition of the sum of an empty set being 0, which I got > burned on myself a while back. > > You could feasibly use: > > Res <- rowSums(testDat, na.rm = TRUE) > is.na(Res) <- rowSums(is.na(testDat)) == ncol(testDat) > > HTH, > > Marc Schwartz > > ______________________________________________ > 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. -- Chuck Cleland, Ph.D. NDRI, Inc. (www.ndri.org) 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894 ______________________________________________ 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.