| Generating Data with DO Loops |
| Iteratively Processing Data Read from a Data
Set |
| So far, you have seen examples of DATA steps that use DO loops to generate
one or more observations from one iteration of the DATA step. Now, let's
look at a DATA step that reads a data set to compute the value of a new variable.
The SAS data set Finance.Cdrates, shown below, contains interest rates for certificates of deposit (CDs) that are available from several institutions. |
SAS Data Set Finance.Cdrates
Institution
Rate
Years
MBNA America
0.0817
5
Metropolitan Bank
0.0814
5
Standard Pacific
0.0806
5
Suppose you want to compare how much each CD will earn at maturity with
an investment of $5,000. The DATA step below creates a new data set,
Work.Compare, that has the added variable,
Investment. |
data work.compare(drop=i);
set finance.cdrates;
Investment=5000;
do i=1 to years;
investment+rate*investment;
end;
run;
|
SAS Data Set Work.Compare
|
The index variable is only used to execute the DO loop, so it is dropped
from the new data set. Notice that the data set variable Years
is used for the stop value in the iterative DO statement. By using this data
set variable, the DO loop executes the number of times specified by the current
value of Years.
During each iteration of the DATA step,
At the bottom of the DATA step, the first observation is written to the
Work.Compare data set. Control returns to the top of the
DATA step, and the next observation is read from
Finance.Cdrates. These steps repeat for each observation
in Finance.Cdrates. The resulting data set contains the
computed values of |
SAS Data Set Work.Compare
Institution
Rate
Years
Investment
MBNA America
0.0817
5
7404.64
Metropolitan Bank
0.0814
5
7394.38
Standard Pacific
0.0806
5
7367.07
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Copyright © 2002 SAS Institute Inc.,
Cary, NC, USA. All rights reserved.