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) This is such a core capability. I would like to see it in the R-Wiki but could not find it there. -- Farrel Buchinsky, MD Pediatric Otolaryngologist Allegheny General Hospital Pittsburgh, PA ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
