Date:         Thu, 13 Dec 2001 20:01:04 -0500
Reply-To:     Perry Watts <wattsp@DCA.NET>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Perry Watts <wattsp@DCA.NET>
Subject:      Nested Whitlock Do Loops?
Comments: To: kitzmann.daniel@MAYO.EDU
Content-Type: text/plain; charset="iso-8859-1"

Date:    Thu, 13 Dec 2001 09:51:43 -0600
From:    "Kitzmann, Daniel J." <kitzmann.daniel@MAYO.EDU>
Subject: Nested Whitlock Do Loops?

Daniel,
In response to:
>Can both counters be created in a single data step employing nested special
>do loops?  For instance, something perhaps in the form of

>data;
> do n_genus = 1 by 1 until (last.genus);
>    do n_species = 1 by 1 until (last.species);
>    . . . .
>    end;
>  end;

The following calculates the number of genera (pl of genus :) ) within
a family and the number of species within a genus. Is this what you
are looking for?

Perry


    data genus;
      length family genus species $15;
      input family genus species;
      cards;
      Cat HouseCats Tabby
      Cat HouseCats Persian
      Cat HouseCats Siamese
      Cat WildCats Cheetah
      Cat WildCats Jaguar
      Cat WildCats Leopard
      Bear CanadaBear PolarBear
      Bear USABear BrownBear
      Bear USABear BlackBear
      Bear USABear GrizzlyBear
      Bear FictionBear TeddyBear
      Bird SmallBird Starling
      Bird MediumBird Duck
      Bird MediumBird Goose
      Bird SmallBird Robin
     run;
    proc sort data=genus;
      by family genus species;
    run;

    *-- the number of genera and species cannot exceed # obs in data set ;
    proc sql noprint;
      select left(put(nobs,8.)) into :nobs
      from dictionary.tables
      where libname eq 'WORK' and memname eq 'GENUS';
    quit;

    data countem;
     do n_genus = 1 to &nobs until (last.family);
       do n_species = 1 to &nobs until (last.genus);
         set genus;
         by family genus;
         output;
       end;
     end;
    run;

    proc print data=countem;
      title1 'countem: FAMILY and GENUS Counts';
      var family genus n_genus species n_species;
    run;

  /******************************************************
   Output:
                   countem: FAMILY and GENUS Counts

 Obs    family    genus          n_genus    species        n_species

   1     Bear     CanadaBear      1       PolarBear         1
   2     Bear     FictionBear       2       TeddyBear        1
   3     Bear     USABear          3       BlackBear         1
   4     Bear     USABear          3       BrownBear       2
   5     Bear     USABear          3       GrizzlyBear       3
   6     Bird     MediumBird       1       Duck                1
   7     Bird     MediumBird       1       Goose              2
   8     Bird     SmallBird           2       Robin               1
   9     Bird     SmallBird           2       Starling             2
  10     Cat      HouseCats        1       Persian             1
  11     Cat      HouseCats        1       Siamese            2
  12     Cat      HouseCats        1       Tabby              3
  13     Cat      WildCats          2       Cheetah            1
  14     Cat      WildCats          2       Jaguar               2
  15     Cat      WildCats          2       Leopard            3
 *****************************************************/

--------------------------
Perry Watts
wattsp@dca.net
--------------------------