getvartypecount() macro function

In a prior post, I made mention of the isblank() and getattr() macro functions. I was hoping to find a way to return the number of character or numeric variables in a SAS data set using the ATTRN() SAS function. Alas, the ATTRN() function does not support what I desired neither and does DICTIONARY.TABLES (except in SAS 9.2 (TS2MO) per http://codecraftersinc.com/ Dictionary Tables Reference Card where the num_character and num_numeric columns existed), so I wrote my own custom macro function.

The reason I wanted this was to dynamically set the dimension of an ARRAY that can only be a numeric constant, numeric expression or a constant. This concept works because the macro is resolved prior to the data step, this is the key to assigning the array dimension without an error. This macro function will probably tied into a subsequent post utilizing this function but here is a sneak peak at what I am trying to do:

data x ;
  if 0 then set sashelp.class ; /* Prime the PDV */
  array achar[ * ] _character_ ;
  array acount[ %getvartypecount( dsn = sashelp.class, type = C ), 2 ] ;

  /* .... more code goes here */

run ;

Below is the actual source code used to create the macro. Notice that it does use the %isblank() function referenced in the hyperlink of the first paragraph.

/**************************************************************************
*     Program: getvartypecount.sas
*      Author: Tom Bellmer
*     Created: 26Apr2017
* SAS Version: 9.3 (TS2M2)
*     Purpose: returns number of Character or Numeric columns in a data set  
*       Usage: %let x = %getvartypecount( dsn = sashelp.class, type = C ) ;
*       Notes: Great use to declare ARRAY dimensions since they expect
*              a numeric constant, numeric expression or constant.  Macros
*              are resolved prior to data step code so this works.
**************************************************************************/
 
%macro getvartypecount( dsn =, type = C ) ;
  %local dsid retval i type ;
 
  %if %isblank( &dsn. ) %then %do ;
    %put %str(E)RROR: the DSN value is missing ;
    %return ;
  %end ;
 
  %let retval = 0 ;
 
  %let type = %upcase( &type. ) ;
  %if &type. = C or &type. = N %then %do ;
    %let dsid = %sysfunc( open( &dsn. ) ) ;
    %if &dsid. %then %do ;
      %do i = 1 %to %sysfunc( attrn( &dsid., nvars ) ) ;
        %if &type. = %sysfunc( vartype( &dsid., &i. ) ) 
         %then %let retval = %eval( &retval. + 1 ) ;
      %end ;
      %let dsid = %sysfunc( close( &dsid. ) ) ;
    %end ;
    %else %put %str(E)RROR: Invalid data set name &dsn. ;
  %end ;
  %else %put %str(E)RROR: Only valid TYPE= parameters are C or N ;
 
  &retval. 
%mend ;
 
/* EOF: getvartypecount.sas  */

Column Splitter

I created a report that includes a one page table of contents. Having a single column of all 50 states runs off the page, so I wanted to create additional columns to spread the data horizontally. The %columnSplitter() macro was created to support this capability.

In the below code, several SAS Component Language (SCL) functions are used to process the data. The OPEN() function supports reading data sets in random access instead of sequential access mode. The dsid variable is a pointer to the data set and can be used with many other functions to determine data types, length and number of rows. The %isblank macro code can be found here.

An ARRAY is used to assign the number of columns to create. That value must be determined at compile time, hence the need for the DATA _NULL_ step prior to the assignment of the array subscript. The offset variable is the result by dividing the total number of logical rows by the desired number of columns. The key to the program is the use of the FETCHOBS() function to read a specified row number.

Based on the data type of the &varname variable, a getvarc()/getvarn() function is used to obtain the value of that row. After data for all columns is collected and output, the call missing( of colname[*] ) function is used to reset all array elements to missing. Finally, what gets opened must be closed using the CLOSE() function.

data states ;
  do statecode = 1 to 56 ;
    statename = fipnamel( statecode ) ;
    if statename not in ('Invalid Code', 'District of Columbia' ) then output ;
  end ;
run ;

%macro columnSplitter( 
    columns = 3
  , indsn   =
  , outdsn  =
  , varname =  
) ;

  %local length vartype varnum i j k ;

  %if not %sysfunc( exist( &indsn. ) ) %then %do ;
    %put %str(E)RROR: invalid input data set name: &indsn. ;
    %return ;
  %end ;

  %if %isblank( &indsn. ) %then %do ;
    %put %str(E)RROR: invalid output data set name: &outdsn. ;
    %return ;
  %end ;

  %if %isblank( &varname. ) %then %do ;
    %put %str(E)RROR: invalid variable name: &varname. ;
    %return ;
  %end ;

  data _null_ ;
    dsid = open( "&indsn." ) ;
    varnum = varnum( dsid, "&varname." ) ;
    call symputx( 'varnum', varnum ) ;
    vartype = vartype( dsid, varnum ) ;
    call symputx( 'vartype', vartype ) ;
    call symputx('length',cats(ifc(vartype='C','$',''),varlen(dsid,varnum)));
    dsid = close( dsid ) ;
  run ;

  data &outdsn. ( keep = colname: ) ; 
    array colname[ &columns. ] &length. ; 
    dsid = open( "&indsn." ) ;
    totalobs = attrn( dsid, 'nlobs' ) ;
    offset = ceil( totalobs / &columns. ) ;
    do i = 1 to offset ;
      k = 1 ;
      do j = 0 by offset while( k <= &columns. ) ;
        rc = fetchobs( dsid, i + j ) ;
        if ( i + j ) <= totalobs then do ;
          if "&vartype." = "C" then colname[k] = getvarc(dsid, &varnum.) ;
          else colname[ k ] = getvarn( dsid, &varnum. ) ;
        end ;
        k + 1 ;
      end ;
      output ;
      call missing( of colname[ * ] ) ;
    end ;

    dsid = close( dsid ) ;
    stop ;
  run ;
%mend ;

%columnSplitter(columns=3,indsn=states,outdsn=statessplit3,varname=statename)
%columnSplitter(columns=4,indsn=states,outdsn=statessplit4,varname=statename)