Hi Marie-Pierre, You first should identify wich components of vec are NA, then compute the length.
vec <- c(1, 2, 1, NA, NA, 1, 2, NA, NA, NA, 3, 4, NA, NA) # Which component is NA? wcs<-which(-is.na(vec)) # Number of NA's in vector vec length(wcs) If you need to do the same for many vector, you could try # A simple function to determinate the number of NA components in a vector x count.NAS=function(x) length(which(is.na(x))) # For vec count.NAS(vec) If you have many vector (for example in a matrix), you could use > apply(X,2,count.NAS) Best wishes, Jorge Ivan Velez Valbuena Industrial Engineer Master in Sciences (Candidate) Faculty of Sciences School of Statistics National University of Colombia at Medellin Medellin, Antioquia, Colombia e-mail: [EMAIL PROTECTED] ----- Original Message ----- From: Marie-Pierre Sylvestre <[EMAIL PROTECTED]> Date: Thursday, October 11, 2007 9:47 am Subject: [R] Identifying and characterizing strings of NA in a vector > Dear R users, > > I was wondering if someone could suggest a few lines of code for > my problem. > > I want to count the number and the length of strings of NA in a > vector. > For example: > > vec <- c(1, 2, 1, NA, NA, 1, 2, NA, NA, NA, 3, 4, NA, NA) > > has 2 strings of NA's of length 2 and 1 string of NA' of length 3. > > I can easily count the number of NA's per vector, but I am having > a hard > time counting the number and length of strings of NA's per vector > without relying heavily on loops. I will have to perform this task > for > many vectors. > > Can somebody help? > > many thanks, > > Marie-Pierre > > ______________________________________________ > 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.htmland 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.
