Jason, On Fri, May 29, 2009 at 5:58 PM, Jason Rupert <jasonkrup...@yahoo.com> wrote: > > Jay, > > > Thanks much for the reply. I think you are right about the prob. > Unfortunately, I was not able to find the old emails I had discussing the use > of the more powerful setdiff that essentially inherits from the base class R > setdiff functionality but extends that functionality by now working with > data.frames instead of just a simple array of values. Love this > functionality.
Your previous post is here [1] http://tolstoy.newcastle.edu.au/R/e6/help/09/03/7781.html and my earlier post is here: [2] https://stat.ethz.ch/pipermail/r-devel/2007-December/047706.html (please note that the link in [1] referring to [2] is now broken). As mentioned in [2], the notions of "set" and "element" are ambiguous in the data frame case... what is an element...? a row, a column, or a single entry? > > However, for the following example, > Test1_DF<-data.frame(HouseSize=c(1:100), LandLocation=c("Here")) > Test1_DF<-data.frame(HouseSize=c(1:100), LandLocation=c("Here"), Price = > c("Low")) > Test2_DF<-rbind(Test1_DF, Test1_DF) > setdiff(Test1_DF, Test2_DF) > [1] HouseSize LandLocation Price > <0 rows> (or 0-length row.names) >> setdiff(Test2_DF, Test1_DF) > [1] HouseSize LandLocation Price > <0 rows> (or 0-length row.names) > > I was hoping for this example one of the setdiff's would have returned > essentially Test1_DF, since it is duplicated and that is what is different > between the two dataframes. > > So, I guess I am trying to figure out a way to truely diff the dataframes, > i.e. determine when two data.frames are different from one another and then > receive the output of the results. > > Does this capability exist in a function within a current R package or does > it exist within a typically used pattern to create this functionality? > > Thanks again for any feedback you can provide. Your question speaks to the ambiguity above. For instance, your 2nd example would be solved by a setdiff for data frames that operates column-wise. If that is all you want, then IIRC there are at least 3 independent solutions in [2] to the row-wise problem. It should be easy enough to tweak one of them to operate on columns instead. For an efficient setdiff() for data frames that can decipher on-the-fly which of row/column/entry is desired, I am going to have to defer to the aforementioned Ninjas. :-) > > Also, I tried to determine my Session Info and the packages I have loaded, > but I received the following: >> sessionInfo() > Error in x$Priority : $ operator is invalid for atomic vectors Ninjas. Hope this helps, Jay ______________________________________________ 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.
