[datatable-help] Replace a character in one data table column

[Frank S.]

Thanks for your reply Jim,

I've realized that in my data R recognizes the value "missing" as authentic NA. So, in conclusion, I really have:

> DT

   id       date
1:  1 1997-04-26
2:  1         NA
3:  4 1998-08-25
4:  4         NA
5:  4 1998-11-07

And if I do:

 > sum(is.na(DT$date))

The result is 2. So I've applied your suggestion and there are not changes in date variable. Can you help me?
 		 	   		  
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