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Re: st: eliminate oppositie positive and negative values


From   sara borelli <saraborelli77@yahoo.it>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: eliminate oppositie positive and negative values
Date   Fri, 30 Mar 2007 00:56:22 +0200 (CEST)

Hi Michael,
thank you so much again for your help, I really
appreciate it!
Sara


> Woops, I copied your own syntax errors below. 
> Clearly, yoiu can't have a 
> variable named abs(xm) and the code should be
> changed to absxm.  Also, I would 
> combine replace todrop line in with the gen todrop
> line as one logical 
> condition, since it should be faster that way,
> especially if you are working 
> with a large dataset and many times though the loop.
> 
> Michael
> 
> ----- Original Message ----- 
> From: "Michael Blasnik"
> <michael.blasnik@verizon.net>
> To: <statalist@hsphsun2.harvard.edu>
> Sent: Thursday, March 29, 2007 8:32 AM
> Subject: Re: st: eliminate oppositie positive and
> negative values
> 
> 
> > That wouldn't work because there could be
> offsetting charges and non 
> > offsetting charges on the same date so the sum
> wouldn't be zero.
> >
> > Although there may be better ways to do this,  to
> repeat the loop until there 
> > is nothing to change you can  use while loop that
> continues based on a test.
> >
> > gen abscharge=abs(charge)
> > gen abs(xm)=abs(xm)
> > local go=1
> > while `go' {
> > bysort personid proc date abscharge
> abs(xm)(charge) :
> > gen byte todrop=charge!=charge[_n-1] & _n>1
> > bysort personid proc date abscharge absxm (charge)
> :
> > replace todrop=1 if charge!=charge[_n+1] & _n<_N
> > qui count if todrop==1
> > if r(N)==0 local go=0
> > drop if todrop==1
> > drop todrop
> > }
> >
> >
> > Michael Blasnik
> >
> > ----- Original Message ----- 
> > From: "Ronán Conroy" <rconroy@rcsi.ie>
> > To: <statalist@hsphsun2.harvard.edu>
> > Sent: Thursday, March 29, 2007 5:11 AM
> > Subject: Re: st: eliminate oppositie positive and
> negative values
> >
> >
> >> On 29 Márta 2007, at 02:41, sara borelli wrote:
> >>
> >>> I need to drop the negatives and the positives
> with
> >>> the same date abs(charge) abs(xm) proc personid.
> As
> >>> suggested by Michael Blasnik in a previous
> e-mail I
> >>> runned the following:
> >>
> >> doesn't that mean that the charges for a given
> date should sum to zero?
> >>
> >> If that's the case then can't you just sum the
> charges within each  person 
> >> within each date and check if they are zero?
> >
> > *
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