Hi Stephen, Try out lapply(). It would help you loop through all data frames and sum.
Regards, Vikash On Thu, Oct 16, 2014 at 1:58 AM, Stephen HK Wong <hon...@stanford.edu> wrote: > Dear All, > > I have many 50 objects they are all dataframes. Each dataframe has many > rows and four column. I simply want to do an addition of 3rd and 4th column > and save the result into 5th column. Since there are many dataframes, I > don't want to do it one by one, is there a way to loop through all objects > and perform the similar action ? > > One way I can think of is like this: > > for (i in 1:50){ > get(ls()[i])[,3]+get(ls()[i][,4] > } > > But I don't know how to save the addition result back to 5th column of > each dataframe. > > > Many Thanks! > > > > Stephen HK Wong > > ______________________________________________ > R-help@r-project.org mailing list > 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 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.