Replace all particular values in a data frame

Question

Having a data frame, how do I go about replacing all particular values along all rows and columns. Say for example I want to replace all empty records with NA's (without typing the positions):

df <- data.frame(list(A=c("", "xyz", "jkl"), B=c(12, "", 100)))

    A   B
1      12
2  xyz    
3  jkl 100

Expected result:

    A   B
1  NA   12
2  xyz  NA  
3  jkl  100

Answer 1

Like this:

> df[df==""]<-NA
> df
     A    B
1 <NA>   12
2  xyz <NA>
3  jkl  100