search for: xxxabc

Hi Does anyone know if there is a function similar to as.numeric that will extract a numeric prefix from a string as in the following examples? x<-c(3, "abc", 5.67, "2.4a", "6a", "6b", "2.4.a", 3, "4.2a") df.x<-data.frame(Code=x) x.str<-levels(df.x[,1]) # required function result 2.40 3.00 4.20 5.67 6.00 NA Thanks Mike White