Farrel Buchinsky wrote: > How does one create a vector whose contents is the list of variables in a > dataframe pertaining to a particular pattern? > This is so simple but I cannot find a straightforward answer. > I want to be able to pass the contents of that list to a "for" loop. > > So let us assume that one has a dataframe whose name is Data. And let us > assume one had the height of a group of people measured at various ages. > > It could be made up of vectors Data$PersonalID, Data$FirstName, > Data$LastName, Data$Height.1, Data$Height.5, Data$Height.9, > Data$Height.10,Data$Height.12,Data$Height.20....many many more variables. > > How would one create a vector of all the Height variable names. > > The simple workaround is to not bother creating the vector "Data$Height.1" > "Data$Height.5" "Data$Height.9" "Data$Height.10" > "Data$Height.12""Data$Height.20"...but rather just to use the sapply > function. However with some functions the sapply will not work and it is > necessary to supply each variable name to a function (see thread at > Repeating tdt function on thousands of variables)
vnames <- paste("Height", 1:20, sep=".") for(vn in vnames){ doSomethingWith(Data[[vn]]) } Uwe Ligges > > This is such a core capability. I would like to see it in the R-Wiki but > could not find it there. > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html