Hack 7.3 Concatenating Multiple Directories in a LIBNAME Statement

SAS Programming Professionals,

Did you know that you can concatenate multiple directories together in a LIBNAME statement?

Most programs have a 1-to-1 correlation between a LIBNAME statement and a SAS data library.  However, it doesn’t need to be that way in real life!  You can have multiple directories specified in a LIBNAME statement.  Consider this example:

libname ctemp ("c:\temp", "c:\temp\usertemp");

data class;

set  ctemp.class(where=(sex="M"));

run;

proc sort data=class out=ctemp.sortedmales;

      by descending age;

run;

libname ctemp list;

In the example, we are concatenating two directories (c:\temp and c:\temp\usertemp) together to form the CTEMP SAS data library.  When you use “CTEMP” as the first level of a two-level SAS data set name, SAS will search first c:\temp, and then c:\temp\usertemp for that SAS data set.  If there is a SAS data set with the same name in both libraries, SAS uses the first one it comes across.

Check out the log from this program:

1    libname ctemp ("c:\temp", "c:\temp\usertemp");

NOTE: Libref CTEMP was successfully assigned as follows:

      Levels:           2

      Engine(1):        V9

      Physical Name(1): c:\temp

      Engine(2):        V9

      Physical Name(2): c:\temp\usertemp

2

3    data class;

4    set  ctemp.class(where=(sex="M"));

5

6    run;

The note highlighted in yellow, above shows that SAS recognizes the concatenation of the two directories to form one SAS data library.

NOTE: There were 10 observations read from the data set CTEMP.CLASS.

      WHERE sex='M';

NOTE: The data set WORK.CLASS has 10 observations and 5 variables.

NOTE: DATA statement used (Total process time):

      real time           0.01 seconds

      cpu time            0.01 seconds

The note highlighted in yellow, above shows that SAS read the CLASS data set from the CTEMP directory.  In fact, CLASS is located in c:\temp\usertemp, which is the second directory in the concatenation.

7

8    proc sort data=class out=ctemp.sortedmales;

9        by descending age;

10   run;

NOTE: There were 10 observations read from the data set WORK.CLASS.

NOTE: SAS sort was used.

NOTE: The data set CTEMP.SORTEDMALES has 10 observations and 5 variables.

NOTE: PROCEDURE SORT used (Total process time):

      real time           0.01 seconds

      cpu time            0.01 seconds

The note highlighted in yellow, above shows that SAS stored the SORTEDMALES data set in the CTEMP directory.  By default, SAS stores all new data sets in c:\temp, which is the first directory in the concatenation.

11

12   libname ctemp list;

NOTE: Libref=   CTEMP

      Scope=    DMS Process

      Levels=   2

        -Level 1-

      Engine=   V9

      Physical Name= c:\temp

      Filename= c:\temp

        -Level 2-

      Engine=   V9

      Physical Name= c:\temp\usertemp

      Filename= c:\temp\usertemp

In the example above, the LIST option on the LIBNAME statement is used to list the attributes of the CTEMP libref; including the directories that are concatenated together.

As long as you understand the rules of the road, (SAS processes the first data set it finds with a specific name when traversing the concatenated files; and SAS writes new data sets to the first directory in the concatenation) concatenating directories together for a single SAS data library can be very useful!

The hack above is an excerpt from the book:  Did You Know That?  Essential Hacks for Clever SAS Programmers

https://tinyurl.com/y83aleb4

Best of luck in all your SAS endeavors!

---MMMMIIIIKKKKEEEE

(aka Michael A. Raithel)

Author of the new cult classic for computer programmers:  It Only Hurts When I Hit <ENTER>
Print edition:  http://tinyurl.com/z8bzx2e 
Kindle edition: http://tinyurl.com/zypgqa7