- Contents (1/2)
- Contents (2/2)
- What's New in the 9.4 Base SAS Language Reference: Concepts
- Overview
- SAS System Features
- Universal Printing
- Font Slanting and Emboldening Support
- TrueType Fonts
- Helvetica and Symbola TrueType Fonts
- Avenir Next TrueType Fonts
- Support for SAS DATA Step View Buffers
- Extended Attributes
- Extended Observation Count
- Cross-Environment Data Access (CEDA)
- SMTP Email Authentication Protocol
- LOCKDOWN State Restrictions
- LOCKDOWN Statement Enhancements
- Data File Protection
- Column Headings in VIEWTABLE
- Accessibility
- SAS System Concepts
- Essential Concepts of Base SAS Software
- SAS Processing
- Rules for Words and Names in the SAS Language
- SAS Variables
- Definition of SAS Variables
- SAS Variable Attributes
- Ways to Create Variables
- Variable Type Conversions
- Aligning Variable Values in SAS Output
- Reordering Variables in SAS Output
- Automatic Variables
- SAS Variable Lists
- Dropping, Keeping, and Renaming Variables
- Encrypting Variable Values
- Numerical Accuracy in SAS Software (1/5)
- Numerical Accuracy in SAS Software (2/5)
- Numerical Accuracy in SAS Software (3/5)
- Numerical Accuracy in SAS Software (4/5)
- Numerical Accuracy in SAS Software (5/5)
- Missing Values
- Expressions
- Definitions for SAS Expressions
- Examples of SAS Expressions
- SAS Constants in Expressions
- Definition
- Character Constants
- Using Quotation Marks with Character Constants
- Comparing Character Constants and Character Variables
- Character Constants Expressed in Hexadecimal Notation
- Numeric Constants
- Numeric Constants Expressed in Standard Notation
- Numeric Constants Expressed in Scientific Notation
- Numeric Constants Expressed in Hexadecimal Notation
- Date, Time, and Datetime Constants
- Bit Testing Constants
- Avoiding a Common Error with Constants
- SAS Variables in Expressions
- SAS Functions in Expressions
- SAS Operators in Expressions
- Definitions
- Arithmetic Operators
- Comparison Operators
- The IN Operator
- Numeric Comparisons
- The IN Operator in Numeric Comparisons
- Character Comparisons
- The IN Operator in Character Comparisons
- Logical (Boolean) Operators and Expressions
- The AND Operator
- The OR Operator
- The NOT Operator
- Boolean Numeric Expressions
- The MIN and MAX Operators
- The Concatenation Operator
- Order of Evaluation in Compound Expressions
- Dates, Times, and Intervals
- Error Processing and Debugging
- SAS Output
- By-Group Processing in SAS Programs
- WHERE-Expression Processing
- Definition of WHERE-Expression Processing
- Where to Use a WHERE Expression
- Syntax of WHERE Expression (1/2)
- Syntax of WHERE Expression (2/2)
- Combining Expressions By Using Logical Operators
- Improving Performance of WHERE Processing
- Processing a Segment of Data That Is Conditionally Selected
- Deciding Whether to Use a WHERE Expression or a Subsetting IF Statement
- Optimizing System Performance
- Definitions for Optimizing System Performance
- Collecting and Interpreting Performance Statistics
- Techniques for Optimizing I/O (1/2)
- Techniques for Optimizing I/O (2/2)
- Overview of Techniques for Optimizing I/O
- Using WHERE Processing
- Using DROP and KEEP Statements
- Using LENGTH Statements
- Using the OBS= and FIRSTOBS= Data Set Options
- Creating SAS Data Sets
- Using Indexes
- Accessing Data through SAS Views
- Using Engines Efficiently
- Setting System Options to Improve I/O Performance
- Setting VBUFSIZE= and OBSBUF= for SAS DATA Step Views
- Using the SASFILE Statement
- Using the DATASETS Procedure to Modify Attributes
- Storing Variables as Characters
- Techniques for Optimizing Memory Usage
- Techniques for Optimizing CPU Performance
- Calculating Data Set Size
- Support for Parallel Processing
- Overview
- What Is Threading Technology in SAS?
- How Is Threading Controlled in SAS?
- Threading in Base SAS
- SAS/ACCESS Engines
- SAS Scalable Performance Data Server
- SAS Intelligence Platform
- SAS High-Performance Analytics Portfolio of Products
- SAS Grid Manager
- SAS In-Database Technology
- SAS In-Memory Analytics Technology
- SAS High-Performance Analytics Product Integration
- The SAS Registry
- Printing with SAS
- Universal Printing (1/4)
- Universal Printing (2/4)
- Universal Printing (3/4)
- Universal Printing (4/4)
- What Is Universal Printing?
- Setting Up the Universal Printing Interface and the Default Printing Environment
- Universal Printing Output Formats
- Viewing Universal Printers and Printer Prototypes
- Viewing Universal Printer Settings
- Modifying Universal Printing Printer Settings
- Universal Printing and ODS
- Specifying the Page Orientation for Universal Printing Documents
- Color Support for Universal Printers
- Embedding Non-Viewable Comments in Universal Printing Output
- Configuring Universal Printing Using the Windowing Environment (1/4)
- Configuring Universal Printing Using the Windowing Environment (2/4)
- Configuring Universal Printing Using the Windowing Environment (3/4)
- Configuring Universal Printing Using the Windowing Environment (4/4)
- System Options That Control Universal Printing
- Managing Universal Printers Using the PRTDEF Procedure (1/2)
- Managing Universal Printers Using the PRTDEF Procedure (2/2)
- Forms Printing
- Using Fonts with Universal Printers and SAS/GRAPH Devices (1/4)
- Using Fonts with Universal Printers and SAS/GRAPH Devices (2/4)
- Using Fonts with Universal Printers and SAS/GRAPH Devices (3/4)
- Using Fonts with Universal Printers and SAS/GRAPH Devices (4/4)
- Creating EMF (Enhanced Metafile Format) Graphics Using Universal Printing
- Creating GIF Images Using Universal Printing
- Creating PCL (Printer Command Language) Files Using Universal Printing
- Creating PDF Files Using Universal Printing
- Creating PNG (Portable Network Graphics) Files Using Universal Printing
- Creating PostScript Files Using Universal Printing
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (1/6)
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (2/6)
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (3/6)
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (4/6)
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (5/6)
- Creating SVG (Scalable Vector Graphics) Files Using Universal Printing (6/6)
- Overview of Scalable Vector Graphics in SAS
- Web Server Content Type for SVG Documents
- The SVG Universal Printers and the Output That They Create
- How to Create SVG Documents
- Browser Support for Viewing SVG Documents
- Images in SVG Documents
- Setting the Environment to Create Stand-alone SVG Documents
- Creating Stand-alone SVG Documents Using the ODS PRINTER Destination
- SVG Documents in HTML Files
- Printing an SVG Document from a Browser
- Creating TIFF Images Using Universal Printing
- Creating Animated GIF Images and SVG Documents (1/2)
- Creating Animated GIF Images and SVG Documents (2/2)
- Windowing Environment Concepts
- Introduction to the SAS Windowing Environment
- Managing Your Data in the SAS Windowing Environment
- Introduction to Managing Your Data in the SAS Windowing Environment
- Managing Data with SAS Explorer
- Working with VIEWTABLE (1/2)
- Working with VIEWTABLE (2/2)
- Overview of VIEWTABLE
- Opening a SAS Data Set in a VIEWTABLE Window
- Displaying Table Headers as Names or Labels
- Customizing SAS Explorer for Opening the VIEWTABLE Window
- Order of Precedence for How Column Headings Are Displayed
- Mapping the VIEWTABLE Command to a Function Key
- Temporarily Change Column Headings
- Move Columns in a Table
- Sort by Values of a Column
- Edit Cell Values
- Subsetting Data By Using the WHERE Expression
- Exporting a Subset of Data
- Importing Data into a Table
- DATA Step Concepts
- DATA Step Processing
- Why Use a DATA Step?
- Overview of DATA Step Processing
- Processing a DATA Step: A Walk-through
- About DATA Step Execution (1/2)
- About DATA Step Execution (2/2)
- About Creating a SAS Data Set with a DATA Step
- Writing a Report with a DATA Step (1/2)
- Writing a Report with a DATA Step (2/2)
- The DATA Step and ODS
- DATA Step Processing Time
- Reading Raw Data
- BY-Group Processing in the DATA Step
- Definitions for BY-Group Processing
- Syntax for BY-Group Processing
- Understanding BY Groups
- Invoking BY-Group Processing
- Determining Whether the Data Requires Preprocessing for BY-Group Processing
- Preprocessing Input Data for BY-Group Processing
- How the DATA Step Identifies BY Groups
- Processing Observations in a BY Group
- Using a Name Literal as the BY-Group Variable
- How SAS Determines FIRST.variable and LAST.variable
- Example 1: Grouping Observations by State, City, ZIP code, and Street
- Example 2: Grouping Observations by City, State, ZIP code, and Street
- Example 3: A Change Affecting FIRST.variable
- Processing BY-Groups in the DATA Step (1/2)
- Processing BY-Groups in the DATA Step (2/2)
- Reading, Combining, and Modifying SAS Data Sets
- Definitions for Reading, Combining, and Modifying SAS Data Sets
- Overview of Tools
- Reading SAS Data Sets
- Combining SAS Data Sets: Basic Concepts (1/2)
- Combining SAS Data Sets: Basic Concepts (2/2)
- Combining SAS Data Sets: Methods (1/6)
- Combining SAS Data Sets: Methods (2/6)
- Combining SAS Data Sets: Methods (3/6)
- Combining SAS Data Sets: Methods (4/6)
- Combining SAS Data Sets: Methods (5/6)
- Combining SAS Data Sets: Methods (6/6)
- Error Checking When Using Indexes to Randomly Access or Update Data (1/2)
- Error Checking When Using Indexes to Randomly Access or Update Data (2/2)
- Using DATA Step Component Objects
- Introduction to DATA Step Component Objects
- Using the Hash Object (1/3)
- Using the Hash Object (2/3)
- Using the Hash Object (3/3)
- Why Use the Hash Object?
- Declaring and Instantiating a Hash Object
- Initializing Hash Object Data Using a Constructor
- Defining Keys and Data
- Non-Unique Key and Data Pairs
- Storing and Retrieving Data
- Maintaining Key Summaries
- Replacing and Removing Data in the Hash Object
- Saving Hash Object Data in a Data Set
- Comparing Hash Objects
- Using Hash Object Attributes
- Using the Hash Iterator Object
- Using the Java Object (1/5)
- Using the Java Object (2/5)
- Using the Java Object (3/5)
- Using the Java Object (4/5)
- Using the Java Object (5/5)
- About the Java Object
- CLASSPATH and Java Options
- Restrictions and Requirements for Using the Java Object
- Declaring and Instantiating a Java Object
- Accessing Object Fields
- Accessing Object Methods
- Type Issues
- Java Objects and Arrays
- Passing Java Object Arguments
- Java Exceptions
- Java Standard Output
- Java Object Examples
- Array Processing
- Definitions for Array Processing
- A Conceptual View of Arrays
- Syntax for Defining and Referencing an Array
- Processing Simple Arrays
- Variations on Basic Array Processing
- Multidimensional Arrays: Creating and Processing
- Specifying Array Bounds
- Examples of Array Processing (1/2)
- Examples of Array Processing (2/2)
- DATA Step Processing
- SAS Files Concepts
- SAS Libraries
- SAS Data Sets
- SAS Data Files
- Definition of a SAS Data File
- Differences between Data Files and SAS Views
- Understanding the Observation Count in a SAS Data File
- Understanding an Audit Trail (1/2)
- Understanding an Audit Trail (2/2)
- Definition of an Audit Trail
- Audit Trail Description
- Defining and Using User Variables
- Operation in a Shared Environment
- Performance Implications
- Preservation by Other Operations
- Programming Considerations
- Other Considerations
- Initiating an Audit Trail
- Controlling the Audit Trail
- Reading and Determining the Status of the Audit Trail
- Audit Trails and CEDA Processing
- Examples of Using Audit Trails
- Understanding Generation Data Sets (1/2)
- Understanding Generation Data Sets (2/2)
- Understanding Integrity Constraints (1/3)
- Understanding Integrity Constraints (2/3)
- Understanding Integrity Constraints (3/3)
- Definition of Integrity Constraints
- General and Referential Integrity Constraints
- Preservation of Integrity Constraints
- Indexes and Integrity Constraints
- Locking Integrity Constraints
- Encryption and Integrity Constraints
- Specifying Integrity Constraints
- Specifying Physical Location for Inter-Libref Referential Integrity Constraints When Sharing Disk Space
- Listing Integrity Constraints
- Rejected Observations
- Integrity Constraints and CEDA Processing
- Examples
- Understanding SAS Indexes (1/5)
- Understanding SAS Indexes (2/5)
- Understanding SAS Indexes (3/5)
- Understanding SAS Indexes (4/5)
- Understanding SAS Indexes (5/5)
- Definition of SAS Indexes
- Benefits of an Index
- The Index File
- Types of Indexes
- Deciding Whether to Create an Index
- Guidelines for Creating Indexes
- Creating an Index
- Using an Index for WHERE Processing
- Using an Index for BY Processing
- Using an Index for Both WHERE and BY Processing
- Specifying an Index with the KEY= Option for SET and MODIFY Statements
- Taking Advantage of an Index
- Procedures and SAS Operations That Maintain Indexes
- Extended Attributes
- Compressing Data Files
- Extending the Observation Count for a 32-Bit SAS Data File (1/2)
- Extending the Observation Count for a 32-Bit SAS Data File (2/2)
- Definition of Extended Observation Count
- Understanding the Extended Observation Count
- Using the EXTENDOBSCOUNTER= Option
- Recovering from an Exceeded Maximum Observation Count
- Extended Observation Count File Attribute
- Extended Observation Count Behavior Considerations
- Extending the Observation Count in a 64-Bit Operating Environment
- When Extending the Observation Count Is Supported
- SAS Views
- Definition of SAS Views
- Benefits of Using SAS Views
- When to Use SAS Views
- DATA Step Views
- Definition of a DATA Step View
- Creating DATA Step Views
- What Can You Do with a DATA Step View?
- Differences between DATA Step Views and Stored Compiled DATA Step Programs
- Restrictions and Requirements
- Performance Considerations
- Example 1: Merging Data to Produce Reports
- Example 2: Producing Additional Output Files
- PROC SQL Views
- Comparing DATA Step and PROC SQL Views
- SAS/ACCESS Views
- Stored Compiled DATA Step Programs
- Definition of a Stored Compiled DATA Step Program
- Uses for Stored Compiled DATA Step Programs
- Restrictions and Requirements for Stored Compiled DATA Step Programs
- How SAS Processes Stored Compiled DATA Step Programs
- Creating a Stored Compiled DATA Step Program
- Executing a Stored Compiled DATA Step Program
- Differences between Stored Compiled DATA Step Programs and DATA Step Views
- Example of DATA Step Program
- DICTIONARY Tables
- SAS Catalogs
- About SAS/ACCESS Software
- Processing Data Using Cross-Environment Data Access (CEDA)
- SAS 9.4 Compatibility with SAS Files from Earlier Releases
- File Protection
- Definition of a Password
- Assigning Passwords
- Removing or Changing Passwords
- Using Password-Protected SAS Files in DATA and PROC Steps
- How SAS Handles Incorrect Passwords
- Assigning Complete Protection with the PW= Data Set Option
- Encoded Passwords
- Using Passwords with Views
- SAS Data File Encryption
- Blotting Passwords and Encryption Key Values
- Metadata-Bound Libraries
- SAS Engines
- SAS File Management
- External Files
- Industry Protocols Used in SAS
- Recommended Reading
- Glossary (1/7)
- Glossary (2/7)
- Glossary (3/7)
- Glossary (4/7)
- Glossary (5/7)
- Glossary (6/7)
- Glossary (7/7)
- Index (1/6)
- Index (2/6)
- Index (3/6)
- Index (4/6)
- Index (5/6)
- Index (6/6)
Chapter 5
Missing Values
Definition of Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83
Creating Special Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84
Order of Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Numeric Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
Character Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
When Variable Values Are Automatically Set to Missing by SAS . . . . . . . . . . . . . . 86
When Reading Raw Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
When Reading a SAS Data Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
When Missing Values Are Generated by SAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Propagation of Missing Values in Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Invalid Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Invalid Character-to-Numeric Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Creating Special Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Preventing Propagation of Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Working with Missing Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
How to Represent Missing Values in Raw Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
How to Set Variable Values to Missing in a DATA Step . . . . . . . . . . . . . . . . . . . . . 90
How to Check for Missing Values in a DATA Step . . . . . . . . . . . . . . . . . . . . . . . . . 90
Definition of Missing Values
missing value
is a value that indicates that no data value is stored for the variable in the current
observation. There are three types of missing values:
• numeric
• character
• special numeric
By default, SAS prints a missing numeric value as a single period (.) and a missing
character value as a blank space. See “Creating Special Missing Values” on page
84 for more information about special numeric missing values.
83
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