A character vector of length 1 with the desired warning.
maintain.factor.scores
Logical:
If TRUE, conversion of the factor levels is attempted
(like in as.numeric(as.character(f))).
If FALSE, the internal codes of the factor are returned
(like in as.numeric(f)).
See 'Details'. This argument is only evaluated if
transform.factors = TRUE.
force.string
Logical indicating whether columns should be force to
numeric, even if NAs are induced.
If FALSE, affected columns are maintained.
If TRUE, conversion is forced.
transform.factors
Logical indicating whether columns of class
factor should be converted.
If FALSE, columns of class factor are maintained.
If TRUE, conversion of factors is attempted.