Date:         Fri, 17 Mar 2000 09:40:37 -0000
Reply-To:     Nigel.Pain@SCOTLAND.GOV.UK
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Nigel Pain <Nigel.Pain@SCOTLAND.GOV.UK>
Subject:      Re: lag & retain
Comments: To: Philippe.VITE@GEP.FR
Content-Type: text/plain; charset="iso-8859-1"

Philippe

Not sure if it will answer your problem, but one thing I would try is
creating temporary lag variables for RAPH and STATE (eg. L_RAPH and
L_STATE). The LAG function returns the value of the variable WHEN THE LAG
FUNCTION WAS LAST CALLED FOR THAT VARIABLE. So try this:

 DATA roue.fort;
    retain raph state;
    set data;
    length mvt $12;
    l_state=lag(state);
    l_raph=lag(raph);
    if state=l_state then mvt=0;
       else if raph=l_raph then mvt=compress(l_state||"_"||state);
 run;

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Nigel Pain
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-----Original Message-----
From: VITE Philippe [mailto:Philippe.VITE@GEP.FR]
Sent: 17 March 2000 08:49
To: SAS-L@LISTSERV.UGA.EDU
Subject: lag & retain



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Hi everybody,

        My pb is the following.

        I have n processes in my table, indexed by T (n*T rows).

        The state of each process (Raph) is indicated by the variable
'state'.

        I want to create a variable movement 'mvt' : each time a raph goes
from one value of state to another value of state, i want mvt to be
oldstate_newstate.

        I tried to do this in a data step using RETAIN and LAG. But it does
not work properly.

        Here's my programm :

 DATA roue.fort;
    retain raph state;
    set data;
    length mvt $12;
    if state=lag(state) then mvt=0;
       else if raph=lag(raph) then mvt=compress(lag(state)||"_"||state);
     run;


The result is that mvt appears to be different from zero at the relevent
times, but i get :

mvt=newstate_newstate instead of oldstate_newstate.


        It can be done in 2 datasteps, but I would be ashamed to do so...


        Any help would be very appreciated.

Philippe.





> Philippe Vité
> --------------------------------------------------------------------------
> Paribas - Nouvelles Technologies - Méthodes Statistiques
> 5, av Kléber, bureau 584.
> 75016 Paris
> 01 40 67 40 16
> philippe.vite@gep.fr

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