Conditional operators in SAS
- Conditional (or) comparison operators:
Conditional operators in SAS
| Symbol | Mnemonics |
| > | gt |
| < | lt |
| >= | Grater than equal to |
| <= | Less than equal to |
| = | Equal to |
| ~= | Negation equal to |
x
2.Logical operator:
| Symbol | Mnemonics |
| & | And |
| | | Or (between in not in like) |
Different conditional statements:
- Where statement(expression)
- If –else statement
- If –else if – else if ….else statement
- Do block
- Do while loop
- Do until loop
- Do loop
Where statement(expression):
Using where statement, we can create subset of data for reporting (temporary) and storage(permanent). If we write where statement in procedure block its create subset data for reporting and data set block for storage.
Ex:
Data company;
Input cname $ Area $ invest strength;
Cards;
Satyam Vizag 2000000 567
TCS HYD 5000000 956
CTS HYD 6000000 345
TCS Madras 5000000 678
Wipro HYD 7000000 789
Wipro Bngl 6700000 456
Satyam Bngl 6700000 453
Wipro Pune 6700000 789
HSBC HYD 8900000 673
ICICI Bngl 8000000 898
HDFC Pune 9000000 796
;
/* Reporting*/
Ex:
Proc print data = company;
Where cname = ‘Satyam’;
Run;
/* Storage*/
Ex;
Data Satyam;
Set company;
Where Cname =’Satyam’;
Run;
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Logical error:
If condition or logical is wrong in statement, then your conditional required data not available in data set. Then in this case we will get logical error. This is one type of execution error.
Indication:
No observation are selected it is the indication of logical error.
Ex:
/* Reporting */
Proc print data = company;
Where Cname =’Satyam’ and invest ge 6000000;
Run;
Ex:
/* Reporting */
Proc print data = company;
Where Cname =’Satyam’ or Cname =’TCS’
Run;
Ex:
/* Reporting */
Proc print data = company;
Where invest between 6000000 and 8000000
Run;
Ex:
/* To report all company data except Satyam */
Proc print data = company;
Where Cname ne ’Satyam’ ;
Run;
Ex:
/* To report all company data except Satyam and TCS*/
Proc print data = company;
Where Cname ne ’Satyam’ or Cname ne ‘TCS’ ;
Run;
Ex:
Proc print data =company;
Where Cname ne ’Satyam’ and Cname ne ‘TCS’;
Run;
Note:
If we use ‘or’ instead of ‘and’ it shows overall data in output.
Ex:
/* to report Satyam or TCS */
Proc print data = company;
Where (Cname eq ’Satyam’ or Cname eq ‘TCS’)
And invest >= 5000000;
Run;
(or)
Where invest >= 5000000 and (Cname eq ’Satyam’ or Cname eq ‘TCS’);
Ex:
Proc print data = company;
Where invest between
2000000 and 5000000 ;
Run;
(or)
Proc print data = company;
Where invest >=2000000 and invest<=5000000 ;
Run;
(or)
Proc print data = company;
Where 2000000 <= invest <=5000000 ;
Run;
Ex:
Proc print data = company;
Where invest >= 5000000 ;
(or)
Where 5000000 <= invest;
Run;
Ex:
Proc print data = company;
Where (Cname ne ’Satyam’ and Cname ne ‘TCS’)
And invest ge 5000000;
Run;
/* To report numeric missing value */
Ex;
Proc print data =company ;
Where invest eq;
Run;
/* To report non – missing numeric value */
Proc print data =company;
Where invest ne;
Run;
/*To report character memory */
Ex:
Proc print data =company;
Where Cname eq ‘ ‘ or area eq ‘ ‘;
Run;
Ex:
Proc print data =company;
Where Cname = ‘ ‘ ;
Run;
/* To report non –missing observations based on all variables in data set */
Ex;
Proc print data =company;
Where Cname ne ‘ ‘
And area ne ‘ ‘
And invest ne .
And strength ne . ;
Run;
/* To report missing observation */
Ex:
Proc print data =company;
Where Cname eq ‘ ‘
Or area eq ‘ ‘
or invest eq .
or strength eq . ;
Run;
Like operator:
Using like operator, we can produce the result based on part of the matching like operator can be used only for character variable.
Percentage % : indicates ‘n’ number of characters.
Underscore(_) : indicates only one characters
Ex:
Proc print data =company;
Where area like ‘p—-’;
Run;
Ex:
Proc print data =company;
Where Cname eq ‘ HSBC ‘ ;
Run;
Ex:
Proc print data =company;
Where Cname like ‘%l’;
Run;
In operator:
It can be used of ‘or’ operator for required variable. ‘In’ indicates to required values not in non required value.
Ex;
Proc print data =company;
Where Cname = ‘ TCS ‘ or Cname = ‘HSBC’ ;
Run;
Proc print data =company;
Where Cname in (‘TCS’, ‘HSBC’);
Run;
Ex:
Proc print data =company;
Where Cname not in (‘TCS’, ‘HSBC’);
Run;
Input stack:
Whenever we submit application, SAS convert into the binary format and stores in one logical memory unit in SAS. This unit is called input stack.
Process:
Input stack connected to the word scanner. Word scanner connected to the 4 compiler. Word scanner work is to identify word value and send to required word to required compiler. Compiler do the compilation and resend to the compilation coding to word scan. Word scan resend to the input stack input stack execute the program.
Input Buffer:
When SAS system read the input statement, it creates input buffer (LMU) brings variable names and observation.
Program data vector(pdv):
Pdv connected to the input buffer and brings at a time only one observation from input buffer and check the data errors in that observation using 2 automatic variables. –N- , – error.
-N- : indicates the number of observations (or) iteration
-error- : if value is 0 , then there is no error
If value is 1, then error is occurred.
Default can be seen by 2 variables in log window whenever error is occurred. This is LMU. Pdv error checking is completed in raw data, pdv creates and stores the variables and assign required data values for data variables. This is called data set unit.
Descriptor information unit:
This unit is created by the pdv SAS system default stores some information about each and every data set. This information is called descriptor information. If we want to see the information we should use contents procedure.
proc contents data = demo;
Run;
If else statement:
It can be used to run required statement based on condition.
Ex:
Data ‘emp’;
Set emp;
If sale ge 500 then salary – salary +1000;
Else salary = salary+500;
Run;
Proc print data = emp;
Run;
If else if else if …else statement:
Conditions are more we can join else if statement in if else block.
Ex:
Data ‘emp’;
Set emp;
If sale ge 500 then salary – salary +2000;
Else if sale ge 400 and
Sale lt 500 then
Salary = salary +1500;
Else if sale ge 300 and
Sale lt 400 then
Salary = salary +1000;
Elase salary = salary +500;
Run;
Proc print data = emp;
Run;
Based on if statement , we can run only one statement. If we want to run multiple statement we use do block with if statement. Do block with end statement.
Do block:
Ex:
Data emp1;
Set emp;
If sale ge then do;
Nsalary = salary +2000;
Bonus =1000;
End;
Else if sale ge 400 and
Sale lt 400 then do;
N salary = salary +1000;
Bonus =500;
End;
Else do;
N salary = salary +500;
Bonus =300;
End;
run;
ex:
data medi;
input pid d level;
cards;
100 0.9
101 0.3
102 0.2
103 0.5
104 0.7
105 0.4
;
Data medi;
Set medi;
If dlevel le 0.5 then do;
Drug =’col5mg’;
Status =’Normal level’;
End;
Else if 0.5 < d level <= 0.7
Then do;
Drug =’col 10 mg’;
Status = ‘middle level’;
End;
Else do;
Drug =’col 15mg’;
Status = ‘high level’;
End;
Proc print data = medi;
Run;
Loop concept:
It can be used to run required statement multiple times. It must have 3 requirements.
- Loop variable and some value
- Condition
- Increment
Do while loop:
Loop concept mainly to generate data. Do while loop to run the loop while condition is true or until the condition is false.
Data generation:
Using loop concept,We can generate data.
Out put statement:
It can be used to store current observation in current data set.
Syntax:
Output<data set name>;
Ex:
Data one;
X=10; output;
X=5 ; output;
Run;
Proc print data =one;
run;
/* to store required observation in required data sets using with output statement*/
Ex;
Data one two;
X=10; output;
X=5 ; output;
Run;
Proc print data =one;
run;
Proc print data =two;
run;
ex;
data dos1 dos 2 dos 3;
set medi 1;
if drug =’col 5 mg’ then
output dos1;
else if drug =’col10 mg’ then
output dos2;
else output dos3;
run;
Proc print data =dos1;
run;
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