The hash object works
by storing and retrieving data based on lookup keys. The keys and
data are DATA step variables, which you use to initialize the hash
object by using dot notation method calls. You define a key by passing
the key variable name to the DEFINEKEY method. You define data by
passing the data variable name to the DEFINEDATA method. When you
have defined all key and data variables, you must call the DEFINEDONE
method to complete initialization of the hash object. Keys and data
consist of any number of character or numeric DATA step variables.
Note: If you use the shortcut notation
for the ADD or REPLACE method (for example,
h.add(key:99,
data:'apple', data:'orange')) and use the ALL:'YES'
option on the DEFINEDATA method, then you must specify the data in
the same order as it exists in the data set.
Note: The hash object does not
assign values to key variables (for example,
h.find(key:'abc')), and the SAS compiler cannot detect the key and data variable assignments
that are performed by the hash object and the hash iterator. Therefore,
if no assignment to a key or data variable appears in the program,
then SAS will issue a note stating that the variable is uninitialized.
To avoid receiving these notes, you can perform one of the following
actions:
-
Set the NONOTES system option.
-
Provide an initial assignment statement
(typically to a missing value) for each key and data variable.
-
Use the CALL MISSING routine with
all the key and data variables as parameters. Here is an example:
length d $20;
length k $20;
if _N_ = 1 then do;
declare hash h();
rc = h.defineKey('k');
rc = h.defineData('d');
rc = h.defineDone();
call missing(k,d);
end;
For detailed
information about how to use the DEFINEDATA method, see Defining Keys and Data in SAS Language Reference: Concepts.