How to convert entire dataframe to numeric while preserving decimals?

Question

I have a mixed class dataframe (numeric and factor) where I am trying to convert the entire data frame to numeric. The following illustrates the type of data I am working w

Answer 1

> df2 <- data.frame(sapply(df1, function(x) as.numeric(as.character(x))))
> df2
     a b
1 0.01 2
2 0.02 4
3 0.03 5
4 0.04 7
> sapply(df2, class)
        a         b 
"numeric" "numeric"