Yes, it is a little different. Is there a way to get 'yyyy-mm' format? Thanks.
On Wed, Feb 22, 2017 at 2:10 PM, Jim Lemon <drjimle...@gmail.com> wrote: > Hi Lily. > Two problems. You have named the month field "mon" and then refer to > it as "month". Second, as the resolution of as.Date is days, it can't > produce a valid date without specifying the day. Thus: > > df.count.mon<-data.frame(count=sample(1:24,24), > year=rep(2014:2015,each=2),mon=rep(1:12,2)) > # make each day the first day of the month > df.count.mon$time<- > as.Date(paste(df.count.mon$year, df.count.mon$mon,1), > '%Y %m %d') > df.count.mon > count year mon time > 1 22 2014 1 2014-01-01 > 2 12 2014 2 2014-02-01 > ... > You will get values, but I don't think they are the ones you want. > > Jim > > On Thu, Feb 23, 2017 at 6:33 AM, lily li <chocol...@gmail.com> wrote: > > Hi R users, > > > > I have a dataframe, with year, month, day, and other variables. I wanted > to > > calculated monthly values of the variables. For example, there is one > > variable called 'count'. I use the code below to convert daily data to > > monthly data. > > > > df.count.mon = aggregate(count ~ year+month, data= df, sum) > > > > The new dataframe has three columns: year, month, and count. Now I want > to > > add one more column as 'time', which has the format 'yyyy-mm'. I use the > > code below but the new column has all NA values. What is the problem and > > how to solve it? > > > > df.count.mon$time = as.Date(paste(df.count.mon$year, > df.count.mon$month), > > '%Y %m') > > > > I had experience to add one more column with the format 'yyyy-mm-dd', > which > > works, but not with monthly format. 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. > [[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.