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.
The BYTE function will return one character in the ASCII collating sequence.
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;
Obs code 1 AW 2 AX 3 AY 4 AZ 5 BA 6 BB 7 BC 8 BD 9 BE 10 BF