SPSS® 12.0 Command Syntax Reference

838 LOOP—END LOOP
Example
LOOP #I=1 TO Z IF (Y GT 10). /*Loop to X=Z for cases with Y GT 10
COMPUTE X=X+1.
END LOOP.
• The value of X remains unchanged for cases with a missing value for Y or a missing value
for Z (or if Z is less than 1).
Example
MISSING VALUES X(5).
LOOP.
COMPUTE X=X+1.
END LOOP IF (X GE 10). /*Loop until X is at least 10 or missing
• Looping is terminated when the value of X is 5 because 5 is defined as missing for X.
Example
LOOP IF NOT MISSING(Y). /*Loop only when Y isn’t missing
COMPUTE X=X+Y.
END LOOP IF (X GE 10). /*Loop until X is at least 10
• The variable X is unchanged for cases with a missing value for Y, since the loop is never
entered.
Creating Data
A loop structure and an END CASE command within an input program can be used to create
data without any data input. The END FILE command must be used outside the loop (but
within the input program) to terminate processing.
Example
INPUT PROGRAM.
LOOP #I=1 TO 20.
COMPUTE AMOUNT=RND(UNIFORM(5000))/100.
END CASE.
END LOOP.
END FILE.
END INPUT PROGRAM.
PRINT FORMATS AMOUNT (DOLLAR6.2).
PRINT /AMOUNT.
EXECUTE.
• This example creates 20 cases with a single variable, AMOUNT. AMOUNT is a uniformly
distributed number between 0 and 5000, rounded to an integer and divided by 100 to
provide a variable in dollars and cents.
• The END FILE command is required to terminate processing once the loop structure is
complete.
See pp. 503 and 512 for other examples of creating data without any data input.