topic Re: PRXPARSE and negative integers in SAS Programming

PRXPARSE and negative integers

Yoko — Thu, 23 Feb 2023 15:37:02 GMT

Hello,

I have a code somebody wrote:

%let dob = PRXPARSE ("/\d{5} | \d{4} | \d{3} | \d{2} | \d{1} /");

I understand that SAS date is expressed anywhere from 1 to 5 digits.

I think I need to add a negative sign for those who were born before 1960.

Does anybody know how to add it to the code above?

Thank you,

Yoko

Re: PRXPARSE and negative integers

ballardw — Thu, 23 Feb 2023 16:41:20 GMT

If you have a SAS date value then perhaps you should tell us what you are looking for. Searching strings, which is what the PRX functions are for is likely going to be a headache.

If you have a variable that supposedly contains a date of birth and you are looking for those born before 1960 then use the year function.

if year(dateofbirthvariable) < 1960 then /* do what ever is needed*/

There a many functions for working with date, time and datetime values and I am fairly certain they are going to much easier than trying to parse strings.

https://communities.sas.com/t5/SAS-Communities-Library/Working-with-Dates-and-Times-in-SAS-Tutorial/ta-p/424354 has a PDF with much information about dates.

Re: PRXPARSE and negative integers

Yoko — Thu, 23 Feb 2023 17:20:50 GMT

Hello,
This is a part of a large program which identifies valid, invalid, or missing field values for multiple variables. This part is for date of birth (DOB). I found that the program categorises DOB before 1960 as 'INVALID' with %let dob = PRXPARSE ("/\d{5} | \d{4} | \d{3} | \d{2} | \d{1} /"); I suspect that this is because the code categorises any 1-5 positive digits as valid, but categorises negative digits invalid. So, I'm looking for a solution for DOB as SAS date.
Thank you,
Yoko

Re: PRXPARSE and negative integers

ballardw — Thu, 23 Feb 2023 17:54:52 GMT

@Yoko wrote:
Hello,
This is a part of a large program which identifies valid, invalid, or missing field values for multiple variables. This part is for date of birth (DOB). I found that the program categorises DOB before 1960 as 'INVALID' with %let dob = PRXPARSE ("/\d{5} | \d{4} | \d{3} | \d{2} | \d{1} /"); I suspect that this is because the code categorises any 1-5 positive digits as valid, but categorises negative digits invalid. So, I'm looking for a solution for DOB as SAS date.
Thank you,
Yoko

You need to define what an "invalid" date might look like. If the variable is a SAS date value then it can be from the year 1582 to 20,000 (yes a 5-digit year ).

Generally I validate date values when the values are read into SAS as text. The informats that read common date structures will take care of validating whether the string is a valid date and catches the stuff like incorrect leap days and invalid days like November 31, which that code looking at digits would not.

I might look for specific dates, such as 1/1/1900 (a common value for people to use with Microsoft products) or year of 9999 as somewhat common codes from different places.

If you have a reason to believe that your dates should be in a specific range then something like

'01JAN1925'd le DOB le today()

checks for a date of birth between 1 January 1925 and today. Note that your current check will not catch dates of birth in the future. A "valid" number, according to that PRX, of 99999 would correspond to 15 Oct 2233, hardly a likely valid DOB value. In fact, running that code on 23 Feb 2023 any number greater than 23064 would be very suspect for an actual date of birth.

Re: PRXPARSE and negative integers

Yoko — Thu, 23 Feb 2023 19:55:05 GMT

Thank you for sharing your ideas!