Hello, Try
df[df$date >= '2012-01-01'& df$date <= '2013-12-31']$A = etc Hope this helps, Rui Barradas Citando lily li <chocol...@gmail.com>: > Hi R users, > > I have a data frame, and I generate a date column like this: > df$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.htmland provide commented, > minimal, self-contained, reproducible code. [[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.