On Mon, 10 Jul 2006, Laurent Deniau wrote: > I have a data frame with named columns and I would like to know if it is > possible to retrieve a column name once selected:
Not really. df$col1 is a new object which does not know where it came from. If you wanted to do this before selection, then print.name <- function(df, col) struture(df[[col]], from=col) would do the extraction and set an attribute to be consulted later. > print(colnames(df)) # assumes to print "col1" "col2" > print.name(df$col1) # would like to print "col1" > print.name(df$col2) # would like to print "col2" > > So what the print.name function should do? > > My aim is not to print the column name but to select some settings from > the column name withing the function (i.e. print.name), while this > function is applied to several columns of the list/data.frame. Actually, > I solved the problem by providing an extra parameter like: > > print.name(df$col1, "col1") > > but since I may have many of these columns/parameters combination, this > is rather error prone and it would be much better if I could detect > which columns of the data frame I am dealing with. > > Thanks. > > ld. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ [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
