Hi R users, I have a data frame, and I generate a date column like this: df$date = seq(as.Date('2012-01-01'), as.Date('2014-12-31'))
df A B C 1 2 1 2 2 3 3 2 4 So the data frame has 4 columns now. But when I want to change the values of column A for specific dates, such as 2012-01-01 to 2013-12-31, I use the code below: df[date >= '2012-01-01'&date <= '2013-12-31']$A = df[date >= '2012-01-01'&date <= '2013-12-31']$A +2 But it does not work, the date I generate seems not effective. What is the problem? Thanks for your help. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.