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Re: st: RE: forvalues within foreach?


From   <cthompson@dfpm.utah.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: forvalues within foreach?
Date   Tue, 11 May 2004 13:37:38 -0600

Thank you Nick.  The dataset I am working with, however, 
contains non-disjoint records, can the approach you provided be 
modified to address overlapping service dates?  When records do 
overlap, I do not want to double-count.  
--Clint Thompson 



On 11 May 2004 at 20:23, Nick Cox wrote:

> In program 2 you have several problems. 
> 
> The local macro 0 contains what you type 
> after the program name, in your case 
> a (probably unexpanded) varlist. Although 
> the -syntax- statement will expand it, 
> that doesn't affect `0'. So the first step is 
> to go to 
> 
> program var_rep
>  version 8
>  syntax varlist(numeric)
>  local n 10
>  foreach var of local varlist {
>    forvalues i = 14610(1)`n' {
>     replace `var' = 1 if (`i' >= svcdate & `i' <= svcdate_end),
>     by(enrolid)
>    }
>  }
> end
> 
> But that still leaves two bugs that I can see: 
> 
> 1. 14610(1)10 won't go anywhere. You mean 14610/14619. 
> 
> 2. -replace- doesn't take a -by()- option. 
> 
> However, given your problem, a direct attack 
> is possible, I believe, without any loops whatsover or 
> indeed any programs whatsoever. 
> 
> Your structure appears to be 
> 
> enrolid svcdate svcdate_end 
> 
> First check that the dates are 
> the right way round in every case 
> 
> . assert svcdate <= svcdate_end 
> 
> Possibly you even have several 
> records for each person. That's no 
> problem, so long as they are disjoint. 
> 
> For each person, you want #days in 
> service between 1 Jan 2000 and 
> 31 Dec 2001. The length of relevant service is 
> 
> min(svcdate_end, mdy(12,31,2001))  
> -max(mdy(1,1,2000),svcdate) 
> 
> So I think what you want is 
> 
> gen cont = 1 + min(svcdate_end, mdy(12,31,2001)) -
> max(mdy(1,1,2000),svcdate) egen sumservice = sum(cont), by(enrolid) 
> 
> Note the 1, based on the assumption that anyone who 
> arrived and left the same day is regarded as serving 
> 1 day, etc. Delete according to taste. 
> 
> Nick 
> n.j.cox@durham.ac.uk 
> 
> cthompson@dfpm.utah.edu
> 
> > I have two small (and clumsy) programs wherein the objective is 
> > to create a variable for each day over a two year time frame 
> > (01Jan2000 - 31Dec2001) then assign the value 1 if the subject 
> > was on service, as defined by two variables:  svcdate & 
> > svcdate_end.  My programs are pasted below; the first one 
> > (var_gen) generates the variables as expected (note that I 
> > limited variable generation to just the first 10 days in 2000).  The
> > second program, however, executes when run but it does not return a 1
> > where it should.  I suspect that the problem may be with the forvalues
> > loop in the foreach statement.  Any advice or suggestions?  My
> > ultimate objective is to sum the total number of days each subject was
> > on service over the two year period.   Thank you.  Clint Thompson   
> > 
> > Program #1:
> > program var_gen
> > version 8
> > local N 10
> > forvalues i = 1(1)`N' {
> > 	gen day`i' = 0
> > 	}
> > end
> > 
> > 
> > Program #2:
> > program var_rep
> > version 8
> > syntax varlist(numeric)
> > local n 10
> > foreach var of local 0 {
> > 	forvalues i = 14610(1)`n' {
> > 	replace `var' = 1 if (`i' >= svcdate & `i' <= 
> > svcdate_end), by(enrolid)
> > 	}
> > }
> > end
> 
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