SAS Arrays : Introduction
In the example above, ABC is an array-name, 5 implies the number of variables in array and "a b c d e" are the fields that make up the array.
3. ARRAY ABC[*] X1-X10;
If the variables are of character type then use $ sign before specifying list of variables.
The first time the loop processes, the value of count is 1; the second time, 2; and the third time, 3. At the beginning of the fourth iteration, the value of count is 4, which is found to be greater than the stop value of 3 so the loop stops. However, the value of i is now 4 and not 3, the last value before it would be greater than 3 as the stop value.
Example II. : Extract first letter of all the character variables
Example III. : Extract first letter and fill in the new character variables
Using the OF Operator in a SAS Array
Examples :
array gnp (*) x y z;
The following two statements are equivalent.
mean_score = mean(of gnp(*));
* Calculate the minimum;
min_score = min(of gnp(*));
DO OVER LOOP
The DO OVER loop is one of the most useful DO loops. It can be used with an array when indexing of the array is not needed.
It provides a simple, appropriate way to process a group of variables in a SAS DATA step.
Syntax
Array array-name {number-of-elements} list-of-variables;
Note: You can use [ ] or { } or ( ) for defining number of elements in the ARRAY statement.
Examples
1. ARRAY ABC[5] a b c d e;
2. ARRAY ABC[*] a b c d e;
In the example above, SAS would automatically calculate the number of variables in array.
Where the X1 variable contains the X1 value, X2 contains the X2 value, etc.
4. ARRAY ABC[*] $ X1-X10;
Sample Data
 |
| SAS Array : Example |
data temp;Example I : Numeric variables having value greater than 3 need to be replaced with missing value
input x1 x2 x3 x4$ x5$;
cards;
1 2 3 AA BB
2 3 4 AB CC
3 4 5 AC DD
4 5 6 AD EE
5 6 7 AE FF
6 7 8 AF GG
;
run;
data test;
set temp;
array nvars {3} x1-x3;
do i = 1 to 3;
if nvars{i} > 3 then nvars{i} =.;
end;
run;
 |
| Output : Array Statement |
Why i is 4 in the output data set?
The first time the loop processes, the value of count is 1; the second time, 2; and the third time, 3. At the beginning of the fourth iteration, the value of count is 4, which is found to be greater than the stop value of 3 so the loop stops. However, the value of i is now 4 and not 3, the last value before it would be greater than 3 as the stop value.
Note : We can drop variable "i" with drop statement or drop data set option.Improvised version of the above code
data test;Notes -
set temp;
array nvars (*) _numeric_;
do i = 1 to dim(nvars);
if nvars{i} > 3 then nvars{i} =.;
end;
drop i;
run;
- The "_numeric_" is used to specify all the numeric variables.
- The DIM function returns the number of elements (variables).
Example II. : Extract first letter of all the character variables
data test;Note - The "_character_" is used to specify all the character variables.
set temp;
array cvars (*) _character_;
do i = 1 to dim(cvars);
cvars{i} = substr(cvars{i},1,1);
end;
drop i;
run;
Example III. : Extract first letter and fill in the new character variables
data test;Example IV : Assign Initial Values in a SAS Array
set temp;
array cvars (*) _character_;
array dvars (*) $ x6 X7;
do i = 1 to dim(cvars);
dvars{i} = substr(cvars{i},1,1) ;
end;
drop i;
run;
data abcd;
set temp;
array nvars (*) _numeric_;
array pvars (*) px1 px2 px3;
array pctinc {3} _temporary_ (1.1 , 1.2 ,1.3); do i = 1 to dim(nvars);
pvars{i} = nvars{i} * pctinc{i};
end;
drop i;
run;
Notes -
- In the above example, we are multiplying variables' values with different numbers.
- When the key word _TEMPORARY_ is used in a ARRAY statement, data elements are created but are not stored in the data file.
Example V : Calculate Percentage Growth
data abcd;
set temp;
array nvars(*) _numeric_;
array diff{2} _temporary_;
array percent{2};
do i = 1 to 2;
diff{i} = nvars{i +1} - nvars{i};
percent{i} = diff{i} / nvars{i} ;
end;
drop i;
run;
Using the OF Operator in a SAS Array
Examples :
array gnp (*) x y z;
The following two statements are equivalent.
sumgnp = sum(of gnp(*)) ;*Calculate the mean;
sumgnp = sum(x,y,z);
mean_score = mean(of gnp(*));
* Calculate the minimum;
min_score = min(of gnp(*));
DO OVER LOOP
The DO OVER loop is one of the most useful DO loops. It can be used with an array when indexing of the array is not needed.
data test;
set temp;
array nvars _numeric_;
do over nvars;
if nvars > 3 then nvars = .;
end;
run;