changing factor to numbers without getting NAs

Thanks Duncan,
This type.convert works fine for me and gives me TSTMean with decimal, but I want to add this result as a new column to my df as int or num, how can I do this?
 
Thanks,
Elahe

Hi all,
I have a df which a part of this is:

    TSTMax     :int 213 228 227 281
    TSTMin     :int 149 167 158 176
    TSTMean    :Factor w/94 levels "100,2" , "104,3" , ...
I want to change the TSTMean into numeric but by using as.numeric(as.character(df$TSTMean)) I get too many NAs.
Is there a way to change TSTMean into numeric without those NAs?
I want TSTMean to be at the end like:

    TSTMean  :int 100.2 104.3 .....

You appear to have a comma as the decimal marker, so you can use 
type.convert(as.character(df$TSTMean), dec = ",", as.is = TRUE) instead 
of as.numeric().

A simpler approach might be to avoid getting the factor in the first 
place; if you read this data using read.table, there is the dec option 
to recognize a comma as the decimal separator.

Duncan Murdoch