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Re: st: global keys


From   "Svend Juul" <SJ@SOCI.AU.DK>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: global keys
Date   Fri, 14 Sep 2007 16:36:40 +0200

Michael McCulloch wrote:
 
I have a dataset which contains a variable <site_02> 
containing a long list of tumor ID codes, from which 
I want to keep ten: C180 through C189.
 
Is there a less labor-intensive way to do the following:
 
keep if site_02=="C180" | site_02=="C181" | site_02=="C182" | ///
site_02=="C183" | site_02=="C184" | site_02=="C185" | ///
site_02=="C186" | site_02=="C187" | site_02=="C188" | site_02=="C189"
 
----------------------------------------------------------
 
Yes!  You can:
 
   keep if site_02 >= "C180" & site_02 < "C190"
 
Relational operators also work with strings:
 
" " < "12" < "2" < "A" < "AA" < "Z" < "a"
 
Strings are sorted in dictionary sequence; however, all uppercase
letters come before lowercase, numbers come before letters, and
spaces or blanks come before anythng else.
 
Hope this helps.
Svend
________________________________________________________ 
 
Svend Juul
Institut for Folkesundhed, Afdeling for Epidemiologi
(Institute of Public Health, Department of Epidemiology)
Vennelyst Boulevard 6 
DK-8000 Aarhus C,  Denmark 
Phone, work:  +45 8942 6090 
Phone, home:  +45 8693 7796 
Fax:          +45 8613 1580 
E-mail:       sj@soci.au.dk 
_________________________________________________________ 

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