Date:         Tue, 18 Oct 2005 10:13:30 -0400
Reply-To:     kong1 <kong1@umbc.edu>
Sender:       "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
Comments:     To: Richard Ristow <wrristow@mindspring.com>
From:         kong1 <kong1@umbc.edu>
Subject:      Re: calculation
In-Reply-To:  <5.1.0.14.2.20051017183544.06c5de50@pop.mindspring.com>
Content-Type: text/plain; charset="us-ascii"

Richard,

Thank you very much! It worked out.

Thanks again.

Benny

-----Original Message-----
From: SPSSX(r) Discussion [mailto:SPSSX-L@LISTSERV.UGA.EDU] On Behalf Of
Richard Ristow
Sent: Monday, October 17, 2005 7:04 PM
To: SPSSX-L@LISTSERV.UGA.EDU
Subject: Re: calculation

At 04:20 PM 10/17/2005, Benny Kong wrote:

>We have to calculate two new variables based on another variable, for
>example,
>
>rcdlgth   start  end
>           (TBC)  (TBC)
>2           1     2
>4           3     6
>5           7     11
>6           12    17
>...
>
>RcdLgth is extracted from a data layout file, that is, record length;
>and we need to compute the start column and end column so as to
>compile a syntax to import the data. To illustrate, the first variable
>has a length of 2, then the start column is 1 and end column is 2; the
>second variable is 4 in length, then the start column is 3 and ends in
>the 6th column; so on and so forth. We see a consistent pattern here;
>however, we find it difficulty in computing the two new variables.
>Could someone help us out?

I take it that your input file has the fields in order (I hope to
goodness, with a sequence number so you can check the order), with no
gaps between fields. (Or if there are gaps, they have records with
"record lengths" as well.) If so, I think this is what you want. Code
is tested; this is SPSS draft output. "TBCSTART" and "TBCEND" are the
"to be computed" variables read from your test data. I've generated
variable FIELDNUM.

*...............................
LIST.
|---------------------------|------------------------|
|Output Created             |17 Oct 05  19:00:16     |
|---------------------------|------------------------|
FIELDNUM RCDLGTH TBCSTART TBCEND

      1       2         1       2
      2       4         3       6
      3       5         7      11
      4       6        12      17

Number of cases read:  4    Number of cases listed:  4


NUMERIC START END (F3).
DO IF   MISSING(LAG(rcdlgth)).
  COMPUTE START = 1.
ELSE.
  COMPUTE START = LAG(END)+ 1.
END IF.
  COMPUTE END   = START
                  + rcdlgth
                  - 1.
LIST.
|---------------------------|------------------------|
|Output Created             |17 Oct 05  19:00:17     |
|---------------------------|------------------------|
FIELDNUM RCDLGTH TBCSTART TBCEND START END

      1       2         1       2    1    2
      2       4         3       6    3    6
      3       5         7      11    7   11
      4       6        12      17   12   17

Number of cases read:  4    Number of cases listed:  4