Date:         Tue, 20 Apr 2004 16:42:02 -0400
Reply-To:     Richard Ristow <wrristow@mindspring.com>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
From:         Richard Ristow <wrristow@mindspring.com>
Subject:      Re: Joining two numeric variables
Comments: To: Don Baker <DRRALPH@OU.EDU>
In-Reply-To:  <200404201710.i3KHAJh04429@listserv.cc.uga.edu>
Content-Type: text/plain; charset="us-ascii"; format=flowed

At 01:10 PM 4/20/2004, Don Baker wrote:

>I want to join (concatenate) the values of two numeric variables into
>a new variable.  One variable is a four digit coalition site number
>and the other is a student id number.  By joining the two variables I
>will be able to create a set of unique id numbers across several
>coalition sites.

First, consider not doing it. Most SPSS commands that use a key (SPLIT
FILES, MATCH FILES, AGGREGATE) use a multiple-variable key quite
comfortably; combining to a single variable buys you very little. (RANK
may be an exception, however; its documentation says, "To organize
ranks into subgroups, specify keyword BY followed by the variable whose
values determine the subgroups.The working data file does not have to
be sorted by this
variable." Note 'variable', in the singular.)

Second, you've had two suggestions to do it using string variables. It
is also often done by arithmetic on numeric variables; see example
below. It assumes that student IDs are 6 digits long; adjust as
necessary. (I'm taking the coalition site number as 'more significant'
than the student ID, so it goes at the high end -- the 'left' -- of the
combined number.)

"NEW_ID1" and "NEW_ID2" are identical, except for different formats;
"NEW_ID2" uses N format to display with leading zeroes. Code assumes
that student IDs are 6 digits long; adjust as necessary. SPSS draft output:

DATA LIST LIST / SITE_NO (F4) STDT_ID (F6).
BEGIN DATA.
   17 123456
   17  23456
   17    101
1001 987654
1001  87654
1001    202
END DATA.

NUMERIC NEW_ID1 (F10)
        /NEW_ID2 (N10).

COMPUTE NEW_ID1 = SITE_NO*1E6 + STDT_ID.
COMPUTE NEW_ID2 = SITE_NO*1E6 + STDT_ID.
LIST.

List
SITE_NO STDT_ID    NEW_ID1    NEW_ID2

     17   123456   17123456 0017123456
     17    23456   17023456 0017023456
     17      101   17000101 0017000101
   1001   987654 1001987654 1001987654
   1001    87654 1001087654 1001087654
   1001      202 1001000202 1001000202

Number of cases read:  6    Number of cases listed:  6