Date:         Fri, 8 Aug 2008 08:05:36 -0700
Reply-To:     "dc353@hotmail.com" <dc353@HOTMAIL.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "dc353@hotmail.com" <dc353@HOTMAIL.COM>
Organization: http://groups.google.com
Subject:      missing values
Comments: To: sas-l@uga.edu
Content-Type: text/plain; charset=ISO-8859-1

Hi,

I have a dataset as follows:


DATE   TICKER     TNA

the dataset is sorted by TICKER DATE

There are no missing observations for either TICKER or DATE

Sometimes the first n observations for TNA are missing.  If TNA is
missing for the first observation (for any TICKER) I need to replace
the missing value with the first non missing value for that TICKER.
I'd like to be able to do this with only going through the records
that I need to.  Appreciate any suggestions.

example:

Date   Ticker    Tna
1        abc          .
2        abc          .
3        abc          .
4        abc          5
5        abc          7
6        abc          .
7        abc          .
1        xyz          3
2        xyz          .

need to convert to:


Date   Ticker    Tna
1        abc          5
2        abc          .
3        abc          .
4        abc          5
5        abc          7
6        abc          .
7        abc          .
1        xyz          3
2        xyz          .