Convert Factors to Numeric Variables
DESCRIPTION:
Convert factors in a data structure to numeric vectors.

This function is generic (see Methods); method functions can be written to handle specific classes of data. Classes which already have methods for this function include: factor data.frame

USAGE: 
fac2num(x, ...)
fac2num.default(x, ...)
REQUIRED ARGUMENTS:
x:
An S object.
VALUE:
Returns x unchanged if is.numeric(x) is TRUE. Otherwise generates an error.
EXAMPLES: 
df1 <- data.frame(ordered(rep(c("hi", "low"), 10)),
     factor(rep(c("+","-"), rep(2,5))), x = rnorm(10))
df2 <- fac2num(df1)