Right way to convert data.frame to a numeric matrix, when df also contains strings?

Question

I have a data frame taken from a .csv-file which contains numeric and character values. I want to convert this data frame into a matrix. All containing information is number

Answer 1

data.matrix(SFI)

From ?data.matrix:

Description:

 Return the matrix obtained by converting all the variables in a
 data frame to numeric mode and then binding them together as the
 columns of a matrix.  Factors and ordered factors are replaced by
 their internal codes.