Message-ID: <2341169031.1116944852@Lab26.DOMAIN.IE.PITT.EDU>
Date: 2005-05-24T18:27:32Z
From: sms13+@pitt.edu
Subject: obtaining first and last record for rows with same identifier
I have a dataframe that contains fields such as patid, labdate, labvalue.
The same patid may show up in multiple rows because of lab measurements on
multiple days. Is there a simple way to obtain just the first and last
record for each patient, or do I need to write some code that performs that.
Thanks,
Steven