WHEROBS Macro - Filtered Observation Count

This macro determines the number of rows in a table. If no filter is specified, it delegates the counting to another macro named '%numobs'. If a filter is provided, it uses system functions (OPEN, ATTRN parameterized with 'NLOBSF', CLOSE) to obtain the number of logical observations respecting the condition, which is generally more performant than a DATA step or a SQL COUNT(*).

Data Analysis

Type : CREATION_INTERNE

The script only defines programming logic (macro) without accessing specific data during its compilation.

1 Code Block

MACRO

Explanation :
Definition of the 'wherobs' macro. It checks if the 'mywhere' parameter is empty. If so, it calls '%numobs'. Otherwise, it opens the table via %sysfunc(open(...)) with the filter, retrieves the number of filtered observations via %sysfunc(attrn(..., nlobsf)), and closes the table.

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1	*m204d08b;
2
3	%macro wherobs(dsn,mywhere);
4	%IF %superq(mywhere)= %THEN %DO;
5	%numobs(&dsn)
6	%return;
7	%END;
8	%local dsid rc;
9	%let dsid=%sysfunc(open(&dsn(where=(&mywhere))));
10	%IF &dsid>0 %THEN %DO;
11	%sysfunc(attrn(&dsid,nlobsf))
12	%let rc=%sysfunc(close(&dsid));
13	%END;
14	%ELSE %put ERROR: Could not open dataset %upcase(&dsn).;
15	%mend wherobs;

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