Introduction to SAS Data Set Options

Introduction to
Data Set Options
Mark Tabladillo, Ph.D.
Software Developer, MarkTab Consulting
Associate Faculty University of Phoenix
Faculty,
January 30, 2007

Introduction
• Data set options allow features during
dataset processing
• Most SAS data set options can apply to
either input or output SAS data sets in
DATA steps or procedure (PROC) steps
• Data set options allow the data step to
control variables, observations, security,
t l i bl b ti it
and data set attributes

Outline
• Define data set options
• Provide examples in four categories
• Di
Discuss d t set processing rules
data t i l

Definition
• Data set options specify actions that
apply only to the SAS data set with which
they appear
appear.

http://support.sas.com/onlinedoc/913/getDoc/en/lrcon.hlp/a002612367.htm

Syntax
• Specify a data set option in parentheses
after a SAS data set name. To specify
several data set options separate them
options,
with spaces.
(option-1=value-1<...option-n=value-n>)
(option 1=value 1< option n=value n>)


Quick Examples
• Data set options enable us to perform
operations such as these:
– Renaming variables
– Selecting only the first or last n observations
for processing
– Dropping variables from processing or from
the output data set
– Specifying a password for a data set
– Adding dataset labels

Common Option Categories
• Variable Control
• Observation Control
• Security
S it
• Data Set Attributes

Examples Dataset
data work.sales (drop=i randomState);
length state $2 sales 8 randomState 3;
do i = 1 to 2500;
randomState = round(rand('gaussian',3,1)+0.5);
if randomState in (1,2,3,4,5) then do;
select(randomState);
l t( d St t )
when(1) state='TN';
when(2) state='AL';
when(3) state='GA';
( ) ;
when(4) state='FL';
when(5) state='MS';
end;
sales = int(rand('gaussian' 1000000 500000));
int(rand('gaussian',1000000,500000));
output work.sales;
end;
end;
run;

List of Common Options
SAS Data Set Option Description

Variable DROP= Data Set Excludes variables from
Control Option processing or from output SAS
data sets
KEEP= Data Set Specifies variables for processing
Option
p or for writing to output SAS data
g p
sets

RENAME= Data Set Changes the name of a variable
Option
O i

http://support.sas.com/onlinedoc/913/getDoc/en/lrdict.hlp/a000104210.htm

Examples: Variable Control
data work salesReformat;
work.salesReformat;
set work.sales (drop=sales);
run;

data work.salesReformat2;
set work.sales (keep=state);
run;

proc sort data=work.sales (rename=(state=salesState))
out=work.salesReformat3 (drop=sales);
by salesState;
run;


Observation FIRSTOBS= Data Set Specifies which observation SAS
Control Option processes first

IN= Data Set Option Creates a variable that indicates
whether the data set contributed
data to the current observation
OBS= Data Set Option Specifies when to stop processing
obse a o s
observations

WHERE= Data Set Selects observations that meet the
Option specified condition


Examples: Observation Control
* (obs - firstobs) + 1 = results;
data work.selectObs1;
set work.sales (firstobs=1 obs=200);
( );
run;

data work.selectObs2;
set work.sales (firstobs=200 obs=400);
( );
run;

proc print data=work.sales (obs=25);
run;
;

proc freq data=work.sales (firstobs=1);
tables state;
run;;

proc means data=work.sales (obs=max);
class state;
;
var sales;
run;

Examples: Observation Control
data work combineObs1;
work.combineObs1;
set work.selectObs1 (in=in1) work.selectObs2 (in=in2);
length source $12;
if in1 then source = 'Dataset One';
else if in2 then source = 'Dataset Two';
run;

data work combineObs2;
work.combineObs2;
set work.selectObs1 (in=in1) work.selectObs2 (in=in2);
if in1 and in2 then output;
run;


Security ALTER= Data Set Option Assigns an alter password to a SAS file and
enables access to a password-
protected SAS file
ENCRYPT= Data Set Encrypts SAS data files
Option
PW= Data Set Option Assigns a read, write, or alter password to a
SAS file and enables access to a
password-protected SAS file
READ= Data Set Option Assigns a read password to a SAS file and
enables access to a read-protected
SAS file
WRITE= Data Set Option Assigns a write password to a SAS file and
enables access to a write-protected
SAS file


Examples: Security
data work.secure1 (alter=NoErrors);
set work.sales;
run;

data work.secure2;
set work.sales (alter=NoErrors);
work sales
run;

* Note: A SAS password does not control access to a SAS file beyond the SAS
system.
system You should use the operating system-supplied utilities and file-system
system supplied file system
security controls in order to control access to SAS files outside of SAS.;
data work.secure3 (encrypt=yes pw=Scramble);
set work.sales;
run;

proc sort data=work.secure3 (pw=scramble) out=work.secure4;
by state sales;
y ;
run;

Data Set COMPRESS= Data Set Controls the compression of
Attributes Option observations in an output SAS data
set
GENMAX= Data Set Requests generations for a data set
Option and specifies the maximum number
of versions
INDEX D
INDEX= Data S
Set D fi
Defines i d
indexes when a SAS d
h data set
Option is created

LABEL= Data Set Specifies a label for the SAS data set
Option


Examples: Data Set Attributes
data work.compress1 (compress=yes label=quot;Attempt at Compressionquot;);
set work.sales;
run;

data work masterSalesDataset (genmax=3);
work.masterSalesDataset (genmax 3);
set work.sales;
run;

d t work.masterSalesDataset;
data k t S l D t t
set work.masterSalesDataset work.selectObs1;
run;

data work.masterSalesDataset;
set work.sales work.selectObs1;
run;

Input and Output Datasets
• If a data set option is associated with an
input data set, the action applies to the
data set that is being read.
read
• If the option appears in the DATA
statement or after an output data set
specification in a PROC step, SAS applies
the action to the output data set
set.


Input and Output Datasets
data
d t _null_;
ll
run;

;
data;
run;

data _null_;
set _null_;
null ;
if _n_ ge 0 then put 'hello';
run;

data _null_;
if _n_ ge 0 then put 'hello';
set _null_;
run;

Order of Execution
• When data set options appear on both input and
output data sets in the same DATA or PROC
step, SAS applies data set options to input data
sets before it evaluates programming statements
or before it applies data set options to output
data t
d t sets.
• Likewise, data set options that are specified for
the data set being created are applied after
programming statements are processed.


Order of Execution

data work.salesReformat4 (rename=(sales=monthlySales));
set work.sales;
sales = sales/12;
run;

data work.salesReformat5;
set work.sales (rename=(sales=monthlySales));
monthlySales = monthlySales/12;
run;

Specification Conflicts
• In some instances data set options
instances,
conflict when they are used in the same
statement For example you cannot
statement. example,
specify both the DROP= and KEEP=
options for the same variable in the same
statement.


Statement Definition
• A SAS statement is a series of items that
may include keywords, SAS names,
special characters and operators
characters, operators.
• All SAS statements end with a semicolon.
• A SAS statement either requests SAS to
t t t ith t t
perform an operation or gives information
to th
t the system.
t


Timing Conflicts
• Timing can also be an issue in some
cases. For example, if using KEEP= and
RENAME
RENAME= on a data set specified in the
SET statement, KEEP= needs to use the
original variable names, because SAS will
names
process KEEP= before the data set is
read.
read The new names specified in
RENAME= will apply to the programming
statements that follow the SET statement
statement.

Timing Conflicts

proc sort data=work.sales (keep=sales state
rename=(sales=monthlySales))
out=work.salesReformat6;
out=work salesReformat6;
by state monthlySales;
run;

proc sort data=work.sales (rename=(sales=monthlySales)
keep=sales state)
out=work.salesReformat7;
by state monthlySales;
run;

Overriding System Options
• Many system options and data set options
share the same name and have the same
function.
• The data set option overrides the system
option for the data set in the step in which
p p
it appears.
• System options remain in effect for all
y p
DATA and PROC steps in a SAS job or
session, unless they are respecified.

Conclusion
• DATA set options allow features during
data step processing
• The SAS System Documentation provides
specific details on the syntax

Contact Information
• Mark Tabladillo
MarkTab Consulting
http://www.marktab.com/
http://www marktab com/

Introduction to SAS Data Set Options

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