Hi Subhamitra, Your data didn't make it through, so I guess the first thing is to guess what it looks like. Here's a try at just January and February of 1994 so that we can see the result on the screen. The logic will work just as well for the whole seven years.
# create fake data for the first two months spdat<-data.frame( dates=paste(c(1:30,1:28),c(rep(1,30),rep(2,28)),rep(1994,58),sep="-"), returnA=sample(15:50,58,TRUE),returnB=sample(10:45,58,TRUE)) # I'll assume that the dates in your file are character, not factor spdat$dates<-as.character(spdat$dates) # if you only have to get the monthly averages, it can be done this way spdat$month<-sapply(strsplit(spdat$dates,"-"),"[",2) spdat$year<-sapply(strsplit(spdat$dates,"-"),"[",3) # get the averages by month and year - is this correct? monthlyA<-by(spdat$returnA,spdat[,c("month","year")],mean) monthlyB<-by(spdat$returnB,spdat[,c("month","year")],mean) Now you have what you say you want: monthlyA month: 1 year: 1994 [1] 34.1 ------------------------------------------------------------ month: 2 year: 1994 [1] 33.32143 monthlyB month: 1 year: 1994 [1] 29.7 ------------------------------------------------------------ month: 2 year: 1994 [1] 27.28571 Sorry I didn't use a loop (for(month in 1:12) ... for (year in 1994:2000) ...), too lazy. Now you have to let us know how this information is to be formatted to go into Excel. Excel will import the text as above, but I think you want something that you can use for further calculations. Jim On Fri, Sep 13, 2019 at 12:54 AM Subhamitra Patra <subhamitra.pa...@gmail.com> wrote: > > Dear R-users, > > I have daily data from 03-01-1994 to 29-12-2000. In my datafile, he first > column is date and the second and third columns are the returns of the > country A, and B. Here, the date column is same for both countries. I want > to calculate the monthly average of both country's returns by using a loop, > and then, I want to export the results into excel. > > Please help me in this regard. > > Please find the attached datasheet. > > Thank you. > > -- > *Best Regards,* > *Subhamitra Patra* > *Phd. Research Scholar* > *Department of Humanities and Social Sciences* > *Indian Institute of Technology, Kharagpur* > *INDIA* > > [image: Mailtrack] > <https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality5&> > Sender > notified by > Mailtrack > <https://mailtrack.io?utm_source=gmail&utm_medium=signature&utm_campaign=signaturevirality5&> > 09/12/19, > 08:23:07 PM > ______________________________________________ > 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. ______________________________________________ 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.