24681 - Merge data sets that have an uneven number of members in the BY groups and reset the remaining observations to "missing"

Sample 24681: Merge data sets that have an uneven number of members in the BY groups and reset the remaining observations to "missing"

/***********************************************************************/
/* It is the nature of MERGE to carry values of unique variables       */
/* down the BY-Group.  If you do not want this result, you have        */
/* to add additional coding logic.                                     */
/*                                                                     */
/* In a DATA step, the IN= variables reset when the BY-Group changes.  */
/* If you reset these IN= variables prior to the MERGE statement,      */
/* you can conditionally check to see if an observation is contributed */
/* from a BY-Group with each iteration of the DATA step.  If there are */
/* remaining members of a BY-Group in one data set, set the variables  */
/* to missing (excluding the BY variables).                            */
/*                                                                     */
/* Starting Data:          --->   Desired Results:                     */
/*                                                                     */
/* DATA A        DATA B           DATA NEW                             */
/*                                                                     */
/* ID   X       ID    Y           ID    X    Y                         */
/* 1   11        1   111           1   11  111                         */
/* 1   22        1   222           1   22  222                         */
/* 1   33                          1   33    .                         */
/* 1   44                          1   44    .                         */
/* 1   55                          1   55    .                         */
/***********************************************************************/


data  a;
  input id x;
datalines;
1 11
1 22
1 33
1 44
1 55
;


data b;
  input id y;
datalines;
1 111
1 222
;


/* Reset IN= variables to 'false', or zero.  If an */
/* observation contributes from A and not B, then  */
/* reset Y to missing                              */

data new;
  ina=0;
  inb=0;
  merge a(in=ina) b(in=inb);
  by id;
  if ina and not inb then y=' ';
run;

proc print data=new;
run;

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Obs    id     x     y

 1      1    11    111
 2      1    22    222
 3      1    33      .
 4      1    44      .
 5      1    55      .

Type:	Sample
Topic:	SAS Reference ==> DATA Step SAS Reference ==> Statements ==> File-handling ==> MERGE Common Programming Tasks ==> Combining Data SAS Reference ==> Statements ==> File-handling ==> MERGE ==> with IN=

Date Modified:	2008-01-28 11:08:42
Date Created:	2004-09-30 14:09:03

Product Family	Product	Host	SAS Release
			Starting	Ending
SAS System	Base SAS	All	n/a	n/a

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Sample 24681: Merge data sets that have an uneven number of members in the BY groups and reset the remaining observations to "missing"

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