Hello,

How would I go about telling stata to drop the observations of variable nace_r2, when the first letter is (A, B, D, E, H, L, M, P, Q, R, S, T)?

Also, how do I tell stata to replace the string variable nace_r2 by numeric variable? Or how could I get rid of the letters in front of the numbers of the variable nace_r2?
I've been using destring, replace, but for some reason it doesn't allow me and it says that it's already a numeric variable when it's a str one.

Thanks!

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input int time str2 country str7 nace_r2 str6 value
2007 "AT" "B"    "88.7" 
2008 "AT" "B"    "94.2" 
2009 "AT" "B"    "90.0" 
2010 "AT" "B"    "100.0"
2011 "AT" "B"    "116.0"
2012 "AT" "B"    "119.3"
2013 "AT" "B"    "119.7"
2014 "AT" "B"    "115.4"
2015 "AT" "B"    "105.1"
2016 "AT" "B"    "95.0" 
2017 "AT" "B"    ":"    
2007 "AT" "B05"  ":"    
2008 "AT" "B05"  ":"    
2009 "AT" "B05"  ":"    
2010 "AT" "B05"  ":"    
2011 "AT" "B05"  ":"    
2012 "AT" "B05"  ":"    
2013 "AT" "B05"  ":"    
2014 "AT" "B05"  ":"    
2015 "AT" "B05"  ":"    
2016 "AT" "B05"  ":"    
2017 "AT" "B05"  ":"    
2007 "AT" "B051" ":"    
2008 "AT" "B051" ":"    
2009 "AT" "B051" ":"    
2010 "AT" "B051" ":"    
2011 "AT" "B051" ":"    
2012 "AT" "B051" ":"    
2013 "AT" "B051" ":"    
2014 "AT" "B051" ":"    
2015 "AT" "B051" ":"    
2016 "AT" "B051" ":"    
2017 "AT" "B051" ":"    
2007 "AT" "B052" ":"    
2008 "AT" "B052" ":"    
2009 "AT" "B052" ":"    
2010 "AT" "B052" ":"    
2011 "AT" "B052" ":"    
2012 "AT" "B052" ":"    
2013 "AT" "B052" ":"    
2014 "AT" "B052" ":"    
2015 "AT" "B052" ":"    
2016 "AT" "B052" ":"    
2017 "AT" "B052" ":"    
2007 "AT" "B06"  ":"    
2008 "AT" "B06"  ":"    
2009 "AT" "B06"  ":"    
2010 "AT" "B06"  ":"    
2011 "AT" "B06"  ":"    
2012 "AT" "B06"  ":"    
2013 "AT" "B06"  ":"    
2014 "AT" "B06"  ":"    
2015 "AT" "B06"  ":"    
2016 "AT" "B06"  ":"    
2017 "AT" "B06"  ":"    
2007 "AT" "B061" ":"    
2008 "AT" "B061" ":"    
2009 "AT" "B061" ":"    
2010 "AT" "B061" ":"    
2011 "AT" "B061" ":"    
2012 "AT" "B061" ":"    
2013 "AT" "B061" ":"    
2014 "AT" "B061" ":"    
2015 "AT" "B061" ":"    
2016 "AT" "B061" ":"    
2017 "AT" "B061" ":"    
2007 "AT" "B062" ":"    
2008 "AT" "B062" ":"    
2009 "AT" "B062" ":"    
2010 "AT" "B062" ":"    
2011 "AT" "B062" ":"    
2012 "AT" "B062" ":"    
2013 "AT" "B062" ":"    
2014 "AT" "B062" ":"    
2015 "AT" "B062" ":"    
2016 "AT" "B062" ":"    
2017 "AT" "B062" ":"    
2007 "AT" "B07"  ":"    
2008 "AT" "B07"  ":"    
2009 "AT" "B07"  ":"    
2010 "AT" "B07"  ":"    
2011 "AT" "B07"  ":"    
2012 "AT" "B07"  ":"    
2013 "AT" "B07"  ":"    
2014 "AT" "B07"  ":"    
2015 "AT" "B07"  ":"    
2016 "AT" "B07"  ":"    
2017 "AT" "B07"  ":"    
2007 "AT" "B071" ":"    
2008 "AT" "B071" ":"    
2009 "AT" "B071" ":"    
2010 "AT" "B071" ":"    
2011 "AT" "B071" ":"    
2012 "AT" "B071" ":"    
2013 "AT" "B071" ":"    
2014 "AT" "B071" ":"    
2015 "AT" "B071" ":"    
2016 "AT" "B071" ":"    
2017 "AT" "B071" ":"    
2007 "AT" "B072" ":"    
end