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SAS, Marketing, Predictive Modeling, Statistics

SAS: Verify function to check invalid data

Posted by phillippeng on July 29, 2009

Syntax for verify function:
verify(character_variable, verify_string)

The verify function returns the first position in the character_variable that contains a character that is not in verify_string. If no invalid data exists, the returned value will be 0.

Initial solution:  IF verify(ID, ‘XYZ012345’) then ….;
Suppose ID = ‘X12B44’, the returned value is then 4.

potential problems:
1. varying length of a variable: There are training blanks which are considered as characters and not in the verify_string.
verify(trim(ID), ‘XYZ012345’)
will return 0 for all valid values of ID, even though they are shorter then specified length.
2. Missing value: The expression above will return a 1 for a missing value of ID. Missing values are considered the same as blanks.
Solution: use missing function

Final solution: if verify(trim(ID), ‘XYZ012345’) and not missing(ID) then …;

In SAS 9 or higher version, you can use NOTDIGIT function:
notdigit(character_value) is equivalent to
verify(character_value, ‘0123456789’)

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