Format an object of class proptab for printing depending on its attributes.
# S3 method for proptab
format(x, digits = NULL, percent = NULL,
justify = "right", ...)object of class proptab
number of digits to display
if not NULL, add a percent sign after each value
justification of character vectors. Passed to format.default
other arguments to pass to format.default
This function is designed for internal use only.