Accessing Data and Creating Data Structures - Sas Institute · c. The OBS= option specifies the record number of the first record to read in an input file. d. The MISSOVER option

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Accessing Data and Creating Data StructuresSAS Global Certification Webinar Series

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Michele Ensor Senior ManagerSAS Education

Accessing Data and Creating Data Structures

Becky GrayCertification Exam Developer

SAS Global Certification


3

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4

Base Programming Exam Content Areas

The intended candidate for the SAS Base Programming exam is someone with current SAS programming experience in the following five content areas:

1. Accessing Data

2. Creating Data Structures

3. Managing Data

4. Generating Reports

5. Handling Errors

In addition, candidates should be familiar with the enhancements and new functionality available in SAS 9.4.


5

Base Programming Exam Specifics

The following are specifics of the SAS Base Programming for SAS®9 exam:

• ______ multiple-choice and short-answer questions

• ______ minutes to complete exam

• Closed book

• Exam taken on a computer

• Score received after completing the exam

• Must achieve a score of _____% correct to pass

60-65

110

70


1. Accessing Data



7

Accessing Data

The content area of Accessing Data includes the following topics:

• Use FORMATTED and LIST input to read raw data files.

• Use INFILE statement options to control processing when reading raw data files.

• Use various components of an INPUT statement to process raw data files including column and line pointer controls, and trailing @ controls.

• Combine SAS data sets.

• Access an Excel workbook.


8

Using Formatted and List Input

Formatted input is used to read standard and nonstandard raw data in fixed columns.

The following are some of the common SAS informats:

DATA output-SAS-data-set;INFILE 'raw-data-file' <options>;INPUT pointer-control variable informat … ;

RUN;

$w. $CHARw.

COMMAw.dDOLLARw.d

COMMAXw.dDOLLARXw.d

$UPCASEw.

EUROXw.d

MMDDYYw. DDMMYYw. DATEw.

w.d

PERCENTw.d

YEARw.


9

Using Formatted and List Input

List input is used to read standard and nonstandard raw data separated by a delimiter.

• A space (blank) is the default delimiter.

• Variables must be specified in the order in which they appear in the raw data file.

• The default length for character and numeric variables is eight bytes unless using a LENGTH statement.

DATA output-SAS-data-set;LENGTH variable(s) $ length;INFILE 'raw-data-file' <options>;INPUT variable <$> variable <:informat> … ;

RUN;


10

Question 1

Given the following fixed column raw data file:

Given the following DATA step:

Which SAS data set is created?

a. b.

data people;infile 'people.dat';input @1 Name $5. @7 Gender $1.

@9 Amt dollar3.;run;

Sue F $26 Bobby M $35


11

Question 1

Given the following fixed column raw data file:

Given the following DATA step:

Which SAS data set is created?

a. b.

data people;infile 'people.dat';input @1 Name $5. @7 Gender $1.

@9 Amt dollar3.;run;

Sue F $26 Bobby M $35


12

Question 2

Given the following delimited raw data file:

Given the desired SAS data set:

Which statement correctly reads the raw data file?

a.

b.

c.

input Date:date. Product Quantity;

input Date date. Product $ Quantity;

input Date:date. Product $ Quantity;

12MAR2013 Shirt 101APR13 Toy 2


13

Question 2

Given the following delimited raw data file:

Given the desired SAS data set:

Which statement correctly reads the raw data file?

a.

b.

c.

input Date:date. Product Quantity;

input Date date. Product $ Quantity;

input Date:date. Product $ Quantity;

12MAR2013 Shirt 101APR13 Toy 2


14

Using INFILE Statement Options

Options can be specified in the INFILE statement:

The following are some of the common INFILE statement options:

DLM= DSD

FIRSTOBS= OBS=

INFILE 'raw-data-file' <options>;

MISSOVER


15

Question 3

Which statement is true?

a. The DSD option sets the default delimiter to a comma.

b. The DLM= option is specified in the INPUT statement.

c. The OBS= option specifies the record number of the first record to read in an input file.

d. The MISSOVER option causes SAS to read a new input data record if it does not find values on the current data record.


16

Question 3


a. The DSD option sets the default delimiter to a comma.

b. The DLM= option is specified in the INPUT statement.

c. The OBS= option specifies the record number of the first record to read in an input file.

d. The MISSOVER option causes SAS to read a new input data record if it does not find values on the current data record.


17

Using INPUT Statement Components

Column and line pointer controls can be specified in the INPUT statement.

In addition, the trailing @ and double trailing @ can be specified in the INPUT statement.

@n +n / #n

@ @@


18

Question 4

Which statement is false?

a. The @n column pointer control moves the pointer to column n.

b. The double trailing @ is specified in the INPUT statement.

c. The / line pointer control advances the pointer to column 1 of the next input record.

d. The single trailing @ holds the input record for the execution of the next INPUT statement across iterations of the DATA step.


19

Question 4

Which statement is false?

a. The @n column pointer control moves the pointer to column n.

b. The double trailing @ is specified in the INPUT statement.

c. The / line pointer control advances the pointer to column 1 of the next input record.

d. The single trailing @ holds the input record for the execution of the next INPUT statement across iterations of the DATA step.


20

Accessing and Combining SAS Data Sets

The SET statement is used to read a SAS data set in a DATA step.

Also, the SET statement is used to concatenate data sets. Concatenating copies all observations from the first data set and then copies all observations from one or more successive data sets.

DATA output-SAS-data-set;SET input-SAS-data-set;

RUN;

DATA output-SAS-data-set;SET input-SAS-data-set1 input-SAS-data-set2 … ;

RUN;


21


The MERGE statement with a BY statement enables for match-merging.

Match-merging combines observations from two or more SAS data sets into a single observation by matching up values of one or more common variables.

DATA output-SAS-data-set;MERGE input-SAS-data-set1 input-SAS-data-set2 … ;BY <DESCENDING> by-variable(s);

RUN;


22


The following are a few of the data set options that can be used with the input SAS data set when accessing and combining data sets:

IN= RENAME=

KEEP= DROP=

FIRSTOBS=

OBS=


23

Question 5

Given the SAS data sets Nc and Sc:

Given the following SAS program:

How many variables are in the final data set Both?

data both;set nc sc;

run;


24

Question 5

Given the SAS data sets Nc and Sc:


How many variables are in the final data set Both? 3

data both;set nc sc;

run;


25

Question 6

Given the SAS data sets One and Two:


How many observations are in the final data set All?

data all;merge one(in=a) two(in=b);by ID;if a and not b;

run;


26

Question 6

Given the SAS data sets One and Two:


How many observations are in the final data set All? 1

data all;merge one(in=a) two(in=b);by ID;if a and not b;

run;


27

Accessing an Excel Workbook

The LIBNAME statement can be used to assign a library reference name to a Microsoft Excel workbook assuming SAS/ACCESS Interface to PC File Format is available.

.

LIBNAME libref EXCEL 'Excel-workbook';LIBNAME libref PCFILES PATH='Excel-workbook';LIBNAME libref XLSX 'Excel-workbook';

PROC CONTENTS DATA=libref._ALL_;RUN;

LIBNAME libref CLEAR;


28

Accessing an Excel Workbook

If using the EXCEL or PSFILES engine, worksheet names appear with a dollar sign at the end of the name. A SAS name literal is used to reference the worksheet.

If using the XLSX engine, worksheet names do not appear with a dollar sign at the end of the name.

libref.'Excel-worksheet$'n

libref.Excel-worksheet


29

Question 7

Which program reads a sheet named July from the Excel workbook YR2017.xlsx?

a.

b.

c.

libname myxls excel 'YR2017.xlsx';data july;

set myxls.'July$'n;run;

libname excel pcfiles 'YR2017.xlsx';data july;

set excel.'July$'n;run;

libname myexcel xlsx 'YR2017.xlsx';data july;

set xlsx.July;run;


30

Question 7

Which program reads a sheet named July from the Excel workbook YR2017.xlsx?

a.

b.

c.

libname myxls excel 'YR2017.xlsx';data july;

set myxls.'July$'n;run;

libname excel pcfiles 'YR2017.xlsx';data july;

set excel.'July$'n;run;

libname myexcel xlsx 'YR2017.xlsx';data july;

set xlsx.July;run;


1. Accessing Data



32

Creating Data Structures

The content area of Creating Data Structures includes the following topics:

• Create temporary and permanent SAS data sets.

• Create and manipulate SAS date values.

• Export data to create standard and comma-delimited raw data files.

• Control which observations and variables in a SAS data set are processed and output.


33

Creating SAS Data Sets

The DATA step can be used to create temporary or permanent SAS data sets.

The LIBNAME statement is used to assign a library reference name (libref) to a SAS library.

Note: Work is the default temporary library.

DATA libref.SAS-data-set;<additional SAS statements>

RUN;

LIBNAME libref 'SAS-data-library';


34


Multiple SAS data sets can be created in a DATA step.

The OUTPUT statement is used to direct output to a specific SAS data set.

Note: An OUTPUT statement without arguments writes to every SAS data set listed in the DATA statement.

DATA SAS-data-set-1 < … SAS-data-set-n>;

OUTPUT <SAS-data-set-1 … SAS-data-set-n>;


35


The DATA step is processed in two phases.

Yes

Compile the step

No

Yes

Compilation Phase

Execution Phase

Success?

Initialize PDV to missing

Execute SET statement

Execute other statements

Output to SAS data set

End of file?

Next step

Next step


36

Question 8

Given the following SAS data set and program:


a. A permanent data set is created.

b. The final data set contains six observations.

c. The final data set contains three variables.

d. The DATA step stops execution during the sixth iteration.

data both;set project.orders;Total=Quantity*Price;

run;


37

Question 8

Given the following SAS data set and program:


a. A permanent data set is created.

b. The final data set contains six observations.

c. The final data set contains three variables.

d. The DATA step stops execution during the sixth iteration.

data both;set project.orders;Total=Quantity*Price;

run;


38

Question 9


a. During the compilation phase, variables are assigned missing values.

b. During the compilation phase, the program data vector (PDV) is created.

c. During the execution phase, the descriptor portion of the SAS data set is created.

d. During the execution phase, an input buffer is created if reading data from a SAS data set.


39

Question 9


a. During the compilation phase, variables are assigned missing values.

b. During the compilation phase, the program data vector (PDV) is created.

c. During the execution phase, the descriptor portion of the SAS data set is created.

d. During the execution phase, an input buffer is created if reading data from a SAS data set.


40

Working with SAS Date Values

A SAS date value is stored as the number of days between January 1, 1960 and a specific date.

A SAS date constant is used to refer to a SAS date value in a program.

' ddMMMyyyy ' d


41

Working with SAS Date Values

Functions are used to extract information from a SAS date value or create a SAS date value.

Formats are used to display SAS date values.

Informats are used to convert data to a SAS date value.

MMDDYYw.DDMMYYw.

DATEw.

WORDDATE. WEEKDATE.

YEARw.

MONYYw.

MMDDYYw.DDMMYYw.

DATEw. YEARw.

YEAR QTR MONTH DAY

WEEKDAY TODAY DATE MDY


42

Question 10


Which report output is correct?

a. b.

c. d.

data dates;Birth='15MAY1964'd;Dow=weekday(Birth);Age=(today()-Birth)/365.25;format Birth weekdate.;

run;proc print data=dates noobs;run;


43

Question 10


Which report output is correct?

a. b.

c. d.

data dates;Birth='15MAY1964'd;Dow=weekday(Birth);Age=(today()-Birth)/365.25;format Birth weekdate.;

run;proc print data=dates noobs;run;


44

Exporting to Raw Data Files

ODS statements can be used to create a raw data file.

The EXPORT procedure can be used to create a raw data file.

ODS CSVALL FILE='raw-data-file';SAS code to generate a report(s)

ODS CSVALL CLOSE;

PROC EXPORT DATA=SAS-data-setOUTFILE='raw-data-file'DBMS=CSV|DLM|TAB <REPLACE> <LABEL>;

DELIMITER='char';RUN;


45

Exporting to Raw Data Files

The DATA step can also be used to create a raw data file.

DATA _NULL_;SET input-SAS-data-set;FILE 'raw-data-file' <DSD>;PUT variable variable-n <:format> … ;

RUN;


46

Question 11


a. ODS CSVALL is part of Base SAS.

b. A style template is used when specifying the STYLE= option in the ODS CSVALL statement.

c. SAS/ACCESS Interface to PC Files is needed to use the EXPORT procedure to create a delimited file.

d. The EXPORT procedure can reference a raw data file with the DATA= option and the OUTFILE= option.


47

Question 11


a. ODS CSVALL is part of Base SAS.

b. A style template is used when specifying the STYLE= option in the ODS CSVALL statement.

c. SAS/ACCESS Interface to PC Files is needed to use the EXPORT procedure to create a delimited file.

d. The EXPORT procedure can reference a raw data file with the DATA= option and the OUTFILE= option.


48

Controlling Observations and Variables

The DROP and KEEP statements can be used to control the variables in the output SAS data set.

The DROP= and KEEP= data set options can also be used to determine the variables in the output data set.

DROP variable-list;

KEEP variable-list;

SAS-data-set(DROP=variable-1 < … variable-n>)

SAS-data-set(KEEP=variable-1 < … variable-n>)


49


The WHERE statement and IF statement can be used to control the observations in the output SAS data set.

• The WHERE statement selects observations before they are brought into the program data vector.

• The IF statement selects observations that were read into the program data vector.

WHERE expression;

IF expression;


50


An expression is a sequence of operands and operators that form a set of instructions that define a condition.

Operandscharacter constants, numeric constants, date constants, character variables, and numeric variables

Arithmetic Operators

exponentiation (**), multiplication (*), division (/), addition (+), and subtraction (-)

Comparison Operators

EQ (=), NE, GT (>), LT (<), GE (>=), LE (<=), and IN

Logical Operators AND (&), OR (|), and NOT

Special WHERE Operators

CONTAINS (?), BETWEEN-AND, IS NULL, IS MISSING, LIKE, SAME AND, and ALSO


51

Question 12

Given the following input SAS data set:


How many variables are in the final SAS data set?

data class;set sashelp.class(drop=Sex);keep Name Height Weight;if Age >= 13 then Group='Teen';

run;


52

Question 12



How many variables are in the final SAS data set? 3

data class;set sashelp.class(drop=Sex);keep Name Height Weight;if Age >= 13 then Group='Teen';

run;


53

Question 13


Which step produces an error?

a.

b.

data subset;set employees;Month=month(birth);if state='CA' and Month=3;

run;

data subset;set employees;Month=month(birth);where state='NC' and Month=3;

run;


54

Question 13


Which step produces an error?

a.

b.

data subset;set employees;Month=month(birth);if state='CA' and Month=3;

run;

data subset;set employees;Month=month(birth);where state='NC' and Month=3;

run;


55

Base Programming Exam Preparation

Multiple resources are available for your exam preparation.


56

Books – SAS Product Documentationhttp://support.sas.com/documentation/onlinedoc/base/

Free SAS Product Documentation is available.

http://support.sas.com/documentation/onlinedoc/base/


57

Books – Certification Prep Guidehttps://www.sas.com/sas/books.html

The official prep guide covers all of the objectives tested in the exam.

https://www.sas.com/sas/books.html


58

BASE Programmer Certification Review Series

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Preparing for the Base Programming Exam September 14, 2017

Accessing Data and Creating Data Structures January 18, 2018

Managing Data February 15, 2018

Generating Reports and Test-Taking Strategies March 13, 2018

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59

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Accessing Data and Creating Data Structures - Sas Institute · c. The OBS= option specifies the record number of the first record to read in an input file. d. The MISSOVER option