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Date:         Wed, 18 Sep 2002 06:04:06 -0700
Reply-To:     Mohan Menon <mohmenin@YAHOO.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Mohan Menon <mohmenin@YAHOO.COM>
Subject:      simple data step question
In-Reply-To:  <OF28CE6CE5.67F26238-ON86256BCF.0073BF17@household.com>
Content-Type: text/plain; charset=us-ascii

Hi all

I am trying to understand a simple data step. Here is an example

data test; input a b; datalines; 1 3 1 2 2 3 2 5 2 6 4 5 5 6 run;

proc sort data=test; by a b;

data test2; set test; by a b; length p_treat $20;

retain p_treat;

if first.a then p_treat = _treat_;

if b ne . then _treat='Test'; _treat_=_treat; p_treat=_treat_; run;

OUTPUT

OBS A B P_TREAT _TREAT_ _TREAT

1 1 2 Test Test Test 2 1 3 Test Test Test 3 2 3 Test Test Test 4 2 5 Test Test Test 5 2 6 Test Test Test 6 4 5 Test Test Test 7 5 6 Test Test Test

QUESTION:

I am trying to understand how P_TREAT value in obs 1 gets populated, since P_TREAT values were assigned only at the last data step and is being retained thereafter.

Thanks for your response.

Mohan

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