1. 1
Data Manipulation and Data Management
Day 1, Session IV
M. Amir Hossain, Ph.D.
January 17, 2016
Transformation Expressions
Arithmetic Operations: Following arithmetic operators
are available:
+ Addition.
- Subtraction.
* Multiplication.
/ Division.
** Exponentiation.
2. 2
Transformation Expressions
No two operators can appear consecutively.
Arithmetic operators cannot be implied. For example,
(VAR1)(VAR2) is not a legal specification; you must specify
VAR1*VAR2.
To improve readability, blanks (not commas) can be inserted
before and after an operator.
To form complex expressions, you can use variables, constants,
and functions with arithmetic operators.
Transformation Expressions
The order of execution is functions first, then
exponentiation, then multiplication, division, and
unary, and then addition and subtraction.
Operators at the same level are executed from left to
right.
To override the order of operation, use parentheses.
Execution begins with the innermost set of
parentheses and progresses out.
3. 3
A relation is a logical expression that compares two values using
a relational operator. Relational operators are:
EQ or = Equal to.
NE or ~= ¬ = or <> Not equal to.
LT or < Less than.
LE or <= Less than or equal to.
GT or > Greater than.
GE or >= Greater than or equal to.
Relational Operators
Data Manipulation Commands
COMPUTE
• COMPUTE target variable = expression
Overview
• COMPUTE creates new numeric variables or modifies the
values of existing variables. The variable named on the left of
the equal sign is the target variable. The variables, constants,
and functions on the right side of the equal sign form an
assignment expression.
4. 4
Data Manipulation Commands
Examples
•
• COMPUTE INCREMENT=SALARY-SALBEGIN.
• EXECUTE.
• COMPUTE PINCREM=(INCREMENT/SALBEGIN)*100.
• EXECUTE.
• COMPUTE RAISE=SALARY*0.12.
• EXECUTE.
• COMPUTE NEWSAL1 = SALARY + SALARY*0.10
• EXECUTE.
• COMPUTE NEWSAL2 = SALARY + SALBEGIN*0.10 + EDUC*10
• EXECUTE.
RECODE
RECODE varlist (value list =value)...(value list=value) [INTO varlist] [/varlist...]
Input keywords: LO, LOWEST, HI, HIGHEST, THRU, MISSING, SYSMIS,
ELSE
Output keywords: COPY, SYSMIS
Overview:
• RECODE changes, rearranges, or consolidates the values of an existing
variable. RECODE can be executed on a value-by-value basis or for a
range of values. Where it can be used, RECODE is much more efficient
that the series of IF commands that produce the same transformation.
With RECODE, you must specify the new values.
5. 5
INTO keyword
INTO specifies a target variable to receive recoded values from the original , or
source variables. Source variable remain unchanged after the recode.
INTO must follow the value specification for the source variables that are being
recoded in to the target variables.
The number of target variable must equal the number of source variables.
Example
RECODE SALARY (LO THRU 50000=1)(50001 THRU 75000=2)(75001 THRU HI=3)
INTO SALCAT1.
EXECUTE.
