st: Re: eliminate negative values and their positive counterpart

["Michael Blasnik" <michael.blasnik@verizon.net>]

I'm not sure if you require that the charges exactly offset each other or 
not, but if they do, then this should work:

gen abscharge=abs(charge)
bysort personid proc date abscharge (charge) : gen hasnegative=charge[1]<0
bysort personid proc date abscharge : gen sumcharge=total(charge)
drop if hasnegative & sumcharge==0
drop hasnegative sumcharge

You may want to browse at the dataset prior to issuing the drop command to 
see if it does what you want.

Michael Blasnik

----- Original Message ----- 
From: "sara borelli" <saraborelli77@yahoo.it>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, March 06, 2007 1:48 PM
Subject: st: eliminate negative values and their positive counterpart



> dear satalist members,
>
> This is an exctract of my data:
<snip>
> where the dots indicate that other values for the same
> personid are in between. I need to eliminate the
> negative charges AND their positive counterpart with
> the same proc and date. Thus, for example I need to
> eliminate the negative
> -13 80048    6/7/2001
> AND its positive counterpart with the same proc and
> date:
> +13   80048    6/7/2001,
> and so on.
> I should find a way to construct an algorithm that
> identifies and eliminates the negatives AND their
> poistive counterpart with he same date and procedure,
> but I cannot figure that out.
> Any help would be really appreciated
>
> thanks
> Sara Borelli
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