How to suppress display of data.frame row numbers?

It’s a matter of changing the default argument for row.names in print.data.frame. To do this, I use the formals function. Perhaps even put formals(print.data.frame)$row.names <- FALSE into your .RProfile file, so that it changes the default each time you fire up R.

# Change default argument of print.data.frame
formals(print.data.frame)$row.names <- FALSE