Date:         Mon, 27 Oct 2008 12:11:49 +0000
Reply-To:     franz_cl2003@yahoo.fr
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Franz <franz_cl2003@YAHOO.FR>
Subject:      Numbering missing visits
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Dear all,

How do I count the consecutive missing visitid (M) per PT and get the expected counts below?

pt      visdat          visitid                count (expected)
1       12JAN2008                   1           .
1       20JAN2008                   2           .
1       03FEB2008                   M           1
1       15FEB2008                   M           2
2       03JAN2008                   1           .
2       27JAN2008                   M           1
2       12FEB2008                   2           .
2       25FEB2008                   3           .
2       12MAR2008                   M           1
2       28MAR2008                   M           2
2       19APR2008                   M           3

Many thanks & Kind regards,
Franz