SASSAS LibraryLibrary

And And DatasetsDatasets

Last Updated : 29June, 2004

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Review the concept of SAS data libraries. Review the LIBNAME statement. Review creating a new SAS data set from

an existing data set. Review conditional processing.

SAS FilesSAS Files

SAS data sets and other files are stored in SAS data libraries. SASUSER

WORK

PROG2

SAS Data LibrariesSAS Data Libraries

A SAS data library is a collection of SAS files that are recognized as a unit by SAS on your operating environment.

WORK - temporary library

SASUSER - permanent library

You can create and access your own permanent libraries.

PROG2 - permanent library

WORK

SASUSER

PROG2

SAS Data LibrariesSAS Data Libraries

The physical structure of a SAS data library depends on your operating system.

Directory-based operating systems (Windows or UNIX)any folder or sub-directory

OS/390 systemsspecially formatted sequential file

The LIBNAME StatementThe LIBNAME Statement

The LIBNAME statement establishes the library reference (or libref), which is an alias for the SAS data library.

General form of the LIBNAME statement:

LIBNAME libref 'SAS-data-library' <options>;LIBNAME libref 'SAS-data-library' <options>;

The libref must be 8 characters or fewer.

The LIBNAME Statement: ExamplesThe LIBNAME Statement: Examples

OS/390 Batch and TSOlibname prog2 'edu.prog2.sasdata' disp=shr;

Windows, DOS, and OS/2libname prog2 'c:\prog2';

UNIXlibname prog2 '/user/prog2';

Two-Level SAS Data Set NamesTwo-Level SAS Data Set Names

LibrefSAS Data

Library

SAS Data

libref.SAS-filenamelibref.SAS-filename

The WORK LibraryThe WORK Library

The WORK library is the default library. If you do not specify a library reference on a SAS data set name, SAS assumes the libref is work.

work.fltat1 fltat1

Accessing a Permanent SAS Data SetAccessing a Permanent SAS Data SetThere are two steps when accessing a

permanent SAS dataset:

Use a LIBNAME statement to set up a libref that points to the location of the data set.

Reference the data set using the libref as the first part of the data set name.

If the libref has already been assigned in the SAS session,

you do not need to assign it again.

......

libname prog2 'c:\workshop\winsas\prog2';

proc print data=prog2.test noobs;run;

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

Windows

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

......

libname prog2 '/users/prog2';

proc print data=prog2.test noobs;run;

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

UNIX

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

......

libname prog2 '.prog2.sasdata';

proc print data=prog2.test noobs;run;

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

OS/390

Viewing a Permanent SAS Data SetViewing a Permanent SAS Data Set

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

Creating a Permanent SAS Data SetCreating a Permanent SAS Data SetThere are two steps when creating a

permanent SAS data set:

If the libref has already been assigned in the SAS session, you do not need to assign it again.

1. Use a LIBNAME statement to set up a libref that points to the location you want to save to.

2. Use the libref as the first level of the SAS data set name.

......

libname prog2 'c:\workshop\winsas\prog2';

data prog2.fltat1; infile 'fltat1.dat'; input @1 EmpID $5. @7 HireDate date9. @17 Salary 5.; Bonus=.05*Salary;run;

Creating a Permanent SAS Data SetCreating a Permanent SAS Data Set

Windows

......

libname prog2 '/users/prog2';

data prog2.fltat1; infile 'fltat1.dat'; input @1 EmpID $5. @7 HireDate date9. @17 Salary 5.; Bonus=.05*Salary;run;

Creating a Permanent SAS Data SetCreating a Permanent SAS Data Set

UNIX

...

libname prog2 '.prog2.sasdata';

data prog2.fltat1; infile '.prog2.rawdata(fltat1)'; input @1 EmpID $5. @7 HireDate date9. @17 Salary 5.; Bonus=.05*Salary;run;

Creating a Permanent SAS Data SetCreating a Permanent SAS Data Set

OS/390

...c01s5d1.sas

Create a SAS Data Set with SAS Data Create a SAS Data Set with SAS Data

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

The scores from a final exam are stored in the SAS data set prog2.test. The professor needs to assign each student a passing grade if the score is 0.7 or above and a failing grade otherwise. The variable Score should not appear in the output data set.

Desired OutputDesired Output

The data set work.fnlscores should contain only the variables LName and Grade.

LName Grade

SMITH PassJONES FailedMOORE PassLEE PassLONG FailedGREEN PassFOREMAN Failed

The SET StatementThe SET Statement

Use a SET statement to read a SAS data set.

General form of a SET statement:

The SET statement points to the SAS data set(s) to be read. Options in the SET statement affect how the data is read.

SET SAS-data-set <options>;SET SAS-data-set <options>;

IF-THEN ELSE StatementsIF-THEN ELSE Statements

One method used to assign values or execute statements conditionally is IF-THEN ELSE statements.

IF condition THEN statement; <ELSE IF condition THEN statement;> … <ELSE statement;>

IF condition THEN statement; <ELSE IF condition THEN statement;> … <ELSE statement;>

The LENGTH StatementThe LENGTH Statement

When creating character variables with conditional logic or functions, it is usually a good idea to assign the lengths explicitly using a LENGTH statement.

General form of a LENGTH statement:

LENGTH variable-name <$> length-specification ...;LENGTH variable-name <$> length-specification ...;

The DROP StatementThe DROP Statement

To drop variables that are read or created during the DATA step, use a DROP statement.

General form of a DROP statement:

Variables dropped with a DROP statement are read into the PDV but are not output to the new SAS data set. They are available for processing during the DATA step.

DROP SAS-variable(s);DROP SAS-variable(s);

Creating a Variable with Conditional LogicCreating a Variable with Conditional Logic

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

......

LNAME

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

Compile

GRADE SCORED

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

Execute

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

0.90SMITH

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

True

LNAMEGRADE SCORE

.

D

Pass 0.90SMITH

......

Write out observation to fnlgrades.

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

Pass 0.90SMITH

Implicit Output

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

Pass 0.90SMITH

Implicit Return

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAME

SMITH

GRADE SCORE

.90

D

Reinitialize PDV. Values of variables not read from SAS are set to missing.

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAME

SMITH

GRADE SCORE

.90

D

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAME

SMITH

GRADE SCORE

.90

D

0.57JONES

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.57MOORE 0.85LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAME

SMITH

GRADE SCORE

.90

D

Failed 0.57JONES

False

......Write out observation to fnlgrades.

PDV

data fnlgrades; length Grade $ 6; drop score; set prog2.test; if score>=.7 then Grade='Pass'; else grade='Failed';run;

LName Score

SMITH 0.90JONES 0.85MOORE 0.57LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

Failed 0.57JONES

Implicit Output

......

PDV

data fnlgrades; length Grade $ 6; drop score; set prog2.test; if score>=.7 then Grade='Pass'; else grade='Failed';run;

LName Score

SMITH 0.90JONES 0.85MOORE 0.57LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.

D

Failed 0.57JONES

Implicit Return

......

PDV

data fnlgrades; length Grade $ 6; drop Score; set prog2.test; if Score>=.7 then Grade='Pass'; else Grade='Failed';run;

LName Score

SMITH 0.90JONES 0.85MOORE 0.57LEE 0.98LONG 0.67GREEN 0.70FOREMAN 0.69

LNAMEGRADE SCORE

.Failed 0.57JONES

Continue processing until end of file marker.

proc print data=fnlgrades noobs;run;

Grade LName

Pass SMITHFailed JONESPass MOOREPass LEEFailed LONGPass GREENFailed FOREMAN

Creating a Variable with Conditional LogicCreating a Variable with Conditional Logic

The VAR StatementThe VAR Statement

To control which variables are displayed and the order in which they are displayed, use the VAR statement.

General form of the VAR statement:

VAR SAS-variable … ;VAR SAS-variable … ;

proc print data=fnlgrades noobs; var LName Grade;run;

LName Grade

SMITH PassJONES FailedMOORE PassLEE PassLONG FailedGREEN PassFOREMAN Failed

Using the VAR StatementUsing the VAR Statement

c01s5d2.sas

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