Date:         Tue, 18 Dec 2001 11:43:45 -0500
Reply-To:     "Chakravarthy, Venky" <Venky.Chakravarthy@PFIZER.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "Chakravarthy, Venky" <Venky.Chakravarthy@PFIZER.COM>
Subject:      Re: cumulative sums of a variable
Comments: To: "Philip A. Townsend" <townsend@AL.UMCES.EDU>
Content-Type: text/plain; charset="iso-8859-1"

Philip,

You have already heard from the learned folks on this list. In addition to
their solutions, here is one more. My solution takes advantage of the
ability of the recent versions of SAS to process the _INFILE_ buffer as a
variable. See if this suits your needs:

%macro readwrit ;
    %do i = 1 %to 3 ;
        %do j = 1 %to 25 ;
            filename in&i.&j. "c:\c_data\junk\lib1\f&i._&j..csv" ;
            filename out&i.&j. "c:\c_data\junk\lib2\f&i._&j..csv" ;
            data _null_ ;
               retain z ;
               infile in&i.&j. dlm = "," ;
               if _n_ > 1 then input x y @ ;
               input @ ;
               z + y ;
               if _n_ = 1 then
               _infile_ = _infile_ || ",Cumsum" ;
               else _infile_ = _infile_ || "," || put(z,3.) ;
               file out&i.&j. ;
               put _infile_ ;
            run ;
        %end ;
    %end ;
%mend readwrit ;

%readwrit


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-----Original Message-----
From: Philip A. Townsend [mailto:townsend@AL.UMCES.EDU]
Sent: Tuesday, December 18, 2001 8:48 AM
To: SAS-L@LISTSERV.UGA.EDU
Subject: cumulative sums of a variable


Hello:

I am a low/mid-grade sas user and have a couple of help questions:

(1) I have a series of 75 files with data that exist in 2 levels.  All
files have a "f" as the prefix, then have a first level of 3 values,
that is f1, f12, and f3 and then 25 levels in the second level, i.e.
f1_1 through f1_25 and f2_1 through f2_25, and so on.  I want to
automate reading these csv files into sas data sets that have the same
name levels.  I know I can do this with do loops, but I am having
trouble with the syntax for naming these and assigning them the
appropriate names.

This is the harder one for me:
(2) Once I have these 75 data sets read in (or I can read them in one
at a time), I want to do the following process to each.  Each data set
has two variables, VALUE and COUNT (originally output from a GIS).  I
sort the data by VALUE.  I want to create a new variable with
cumulative sum of COUNT.  That is if my original data are as such:

obs    VALUE    COUNT
1        1              13
2        4              356
3        5              231
4        9              18
5        11             1002
6        12             88

I want an output file created that looks as such:

Obs    VALUE    COUNT    CUMSUM
1        1              13                13
2        4              356               369
3        5              231               600
4        9              18                 618
5        11             1002            1620
6        12             88                 1708

These files will then be output back to CSV files to be read back into
to GIS.

So I want to automate reading in the 75 files with a 2-level naming
convention, determine the cumulative sum of count (with the data
sorted by value) and then write back out to new data sets that follow
similar naming conventions.

Cam anyone provide some help?

Thanks,
Phil Townsend


--

Phil Townsend
Assistant Professor
University of Maryland Center for Environmental Science
Appalachian Laboratory
301 Braddock Road
Frostburg, MD  21532-2307   USA

phone: 301.689.7124   fax: 301.689.7200
email: townsend@al.umces.edu

http://www.al.umces.edu/~townsend