Incrementing Character Values
Incrementing numeric values can be easily achieved using SAS software, but what about incrementing character values?
Let's consider a scenario where we have our starting code AA and we would like to increment this value by a one character each time, so therefore the next code is AB, then AC etc to the value of ZZ.
When incrementing numeric values we can simply add 1 to the value, similarly we can use the same method with character values.
The steps we need to take are:
• Find the ASCII equivalent value for our last character value in our code using the RANK function;
• Find the ASCII equivalent value for our minimum and maximum values so 'A' and 'Z' which are 65 and 90 respectively;
• Increment the ASCII equivalent value by 1 for our code;
• Place the new ASCII value back into a character value using the BYTE function.
The RANK function is used to find the position of a character in the ASCII collating sequence.
Syntax is
RANK(<character string>)
The BYTE function will return one character in the ASCII collating sequence.
Syntax is
BYTE(n)
where n ranges from 0 to 255.
Below is a simple example which starts with the code AW and will then increment the current code value by the next character value for duration of 10 iterations.
data work.code(keep=code);
input code $;
output;
do i=1 to 10;
*Find the ASCII value for the second character value;
last_char=rank(substr(code,2,1))+1;
*If the new last character is higher than Z then set the
letter to A and increment the first character;
if last_char > 90 then do;
last_char=65;
*Find the ASCII value for the first character value;
first_char=rank(substr(code,1,1))+1;
*If the existing code is ZZ then error;
if first_char > 90 then put 'ERROR: No More Unique Codes';
*Replace the first character with new value;
else substr(code,1,1)=byte(first_char);
end;
*Replace the second character with new value;
substr(code,2,1)=byte(last_char);
output;
end;
datalines;
AW
run;
proc print data=new_codes;
run;
Output Window:
Obs code
1 AW
2 AX
3 AY
4 AZ
5 BA
6 BB
7 BC
8 BD
9 BE
10 BF
11 BG
