%DROPMISS - SAS - sas

Question

I've been reading up on how to DROP variables from my dataset that have null values in every observation - it seems the best way to do this is using the %DROPMISS macro function - however I'm getting an error msg - below is the code I'm trying and the error msg
Code
%DROPMISS (DSIN=dataset1, DSOUT=dataset2);
Log
4665 %DROPMISS (DSIN=dataset1, DSOUT=dataset2);
-
180
WARNING: Apparent invocation of macro DROPMISS not resolved.
ERROR 180-322: Statement is not valid or it is used out of proper order.

Answer 1

You need to define the dropmiss macro before you use it.
You can find it here in the appendix (page3)
http://support.sas.com/resources/papers/proceedings10/048-2010.pdf
Or better formatted here:
/******************/
options nomprint noSYMBOLGEN MLOGIC;
/****************************/
%macro DROPMISS( DSNIN /* name of input SAS dataset
*/
, DSNOUT /* name of output SAS dataset
*/
, NODROP= /* [optional] variables to be omitted from dropping even if
they have only missing values */
) ;
/* PURPOSE: To find both Character and Numeric the variables that have only
missing values and drop them if
* they are not in &NONDROP
*
* NOTE: if there are no variables in the dataset, produce no variables
processing code
*
*
* EXAMPLE OF USE:
* %DROPMISS( DSNIN, DSNOUT )
* %DROPMISS( DSNIN, DSNOUT, NODROP=A B C D--H X1-X100 )
* %DROPMISS( DSNIN, DSNOUT, NODROP=_numeric_ )
* %DROPMISS( DSNIN, DSNOUT, NOdrop=_character_ )
*/
%local I ;
%if "&DSNIN" = "&DSNOUT"
%then %do ;
%put /------------------------------------------------\ ;
%put | ERROR from DROPMISS: | ;
%put | Input Dataset has same name as Output Dataset. | ;
%put | Execution terminating forthwith. | ;
%put \------------------------------------------------/ ;
%goto L9999 ;
%end ;
/*###################################################################*/
/* begin executable code
/*####################################################################/
/*===================================================================*/
/* Create dataset of variable names that have only missing values
/* exclude from the computation all names in &NODROP
/*===================================================================*/
proc contents data=&DSNIN( drop=&NODROP ) memtype=data noprint out=_cntnts_( keep=
name type ) ; run ;
%let N_CHAR = 0 ;
%let N_NUM = 0 ;
data _null_ ;
set _cntnts_ end=lastobs nobs=nobs ;
if nobs = 0 then stop ;
n_char + ( type = 2 ) ;
n_num + ( type = 1 ) ;
/* create macro vars containing final # of char, numeric variables */
if lastobs
then do ;
call symput( 'N_CHAR', left( put( n_char, 5. ))) ;
call symput( 'N_NUM' , left( put( n_num , 5. ))) ;
end ;
run ;
/*===================================================================*/
/* if there are no variables in dataset, stop further processing
/*===================================================================*/
%if %eval( &N_NUM + &N_CHAR ) = 0
%then %do ;
%put /----------------------------------\ ;
%put | ERROR from DROPMISS: | ;
%put | No variables in dataset. | ;
%put | Execution terminating forthwith. | ;
%put \----------------------------------/ ;
%goto L9999 ;
%end ;
/*===================================================================*/
/* put global macro names into global symbol table for later retrieval
/*===================================================================*/
%LET NUM0 =0;
%LET CHAR0 = 0;
%IF &N_NUM >0 %THEN %DO;
%do I = 1 %to &N_NUM ;
%global NUM&I ;
%end ;
%END;
%if &N_CHAR > 0 %THEN %DO;
%do I = 1 %to &N_CHAR ;
%global CHAR&I ;
%end ;
%END;
/*===================================================================*/
/* create macro vars containing variable names
/* efficiency note: could compute n_char, n_num here, but must declare macro names
to be
global b4 stuffing them
/*
/*===================================================================*/
proc sql noprint ;
%if &N_CHAR > 0 %then %str( select name into :CHAR1 - :CHAR&N_CHAR from
_cntnts_ where type = 2 ; ) ;
%if &N_NUM > 0 %then %str( select name into :NUM1 - :NUM&N_NUM from
_cntnts_ where type = 1 ; ) ;
quit ;
/*===================================================================*/
/* Determine the variables that are missing
/*
/*===================================================================*/
%IF &N_CHAR > 1 %THEN %DO;
%let N_CHAR_1 = %EVAL(&N_CHAR - 1);
%END;
Proc sql ;
select %do I= 1 %to &N_NUM; max (&&NUM&I) , %end; %IF &N_CHAR > 1 %THEN %DO;
%do I= 1 %to &N_CHAR_1; max(&&CHAR&I), %END; %end; MAX(&&CHAR&N_CHAR)
into
%do I= 1 %to &N_NUM; :NUMMAX&I , %END; %IF &N_CHAR > 1 %THEN %DO;
%do I= 1 %to &N_CHAR_1; :CHARMAX&I,%END; %END; :CHARMAX&N_CHAR
from &DSNIN;
quit;
/*===================================================================*/
/* initialize DROP_NUM, DROP_CHAR global macro vars
/*===================================================================*/
%let DROP_NUM = ;
%let DROP_CHAR = ;
%if &N_NUM > 0 %THEN %DO;
DATA _NULL_;
%do I = 1 %to &N_NUM ;
%IF &&NUMMAX&I =. %THEN %DO;
%let DROP_NUM = &DROP_NUM %qtrim( &&NUM&I ) ;
%END;
%end ;
RUN;
%END;
%IF &N_CHAR > 0 %THEN %DO;
DATA _NULL_;
%do I = 1 %to &N_CHAR ;
%IF "%qtrim(&&CHARMAX&I)" eq "" %THEN %DO;
%let DROP_CHAR = &DROP_CHAR %qtrim( &&CHAR&I ) ;
%END;
%end ;
RUN;
%END;
/*===================================================================*/
/* Create output dataset
/*===================================================================*/
data &DSNOUT ;
%if &DROP_CHAR ^= %then %str(DROP &DROP_CHAR ; ) ; /* drop char variables
that
have only missing values */
%if &DROP_NUM ^= %then %str(DROP &DROP_NUM ; ) ; /* drop num variables
that
have only missing values */
set &DSNIN ;
%if &DROP_CHAR ^= or &DROP_NUM ^= %then %do;
%put /----------------------------------\ ;
%put | Variables dropped are &DROP_CHAR &DROP_NUM | ;
%put \----------------------------------/ ;
%end;
%if &DROP_CHAR = and &DROP_NUM = %then %do;
%put /----------------------------------\ ;
%put | No variables are dropped |;
%put \----------------------------------/ ;
%end;
run ;
%L9999:
%mend DROPMISS ;