Dear All, I wonder how to compute the age from the date of birth and the date of examination. Suppose that have the following data: df <- as.data.frame(rbind(c(1,"10/08/1950","15/03/1998"), c(1,"10/08/1950","20/07/1998"), c(1,"10/08/1950","23/10/1998"))) names(df) <- c("ID", "date_birth", "date_exam") where: date_birth: is the date of birth date_exam: date of examination I used the following program to compute the value of the age : difftime(strptime(as.character(df$date_exam), '%d/%m/%Y'), strptime(as.character(df$date_birth), '%d/%m/%Y'))/365.25 which gives me as an output: > Time differences of 47.59491, 47.94251, 48.20260 days theses values are actually the 3 ages (but
My questions are: 1- Why in the output it says "days" instead of "years") 2- How can I obtain the output as a numeric vector, without the statement "Time difference of ....". This is in order to use it in my calculations. 3- Is there a way quicker and less redondant to compute the age form the date_birth and date_exam? Thanks a lot, Bernard, --------------------------------- [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html