I think we need some actual sample code . Also by= 0 seems a bit funny. --- qian z <qianpland at yahoo.com> wrote: > I used merge() in a function, but it doesn't return > correct data frame. > > add.name <- function(data, x) > > { > > ... > ... > > newfile <- merge(data, resid, by =0, all.x=TRUE, > all.y= FALSE) > newfile > > > } >