Date:         Wed, 15 Mar 2000 13:37:43 EST
Reply-To:     frank.ivis@ices.on.ca
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Frank Ivis <frank.ivis@ICES.ON.CA>
Subject:      Counting problem
Content-type: text/plain; charset=us-ascii

I have data arranged as follows:

id    number
1       7
1       7
2       8
2       8
3       7
3       8
4       8
4       7
4       8
5       .

I would like to create a new variable (screen) that for each id, would
indicate whether the 7 occurs for all records (1), only the 8 occurs (2), both
occur (3) or none occur (4).

The final data would look like this:

id    number  screen
1       7             1
1       7             1
2       8             2
2       8             2
3       7             3
3       8             3
4       8             3
4       7             3
4       8             3
5       .              4

The tricky part is the third condition. I can't figure out how to determine
when the values differ. My final dataset has over 500,000 records, so I'm
hoping there is an efficient solution to this.

I would appreciate it if you could also cc your response to my private email;
I don't always get all the mail from the list.

Thanks in advance for any help,

Frank Ivis