Cool V9 SAS Compress() Function Tricks

In SAS Version 9 there is a new option available for the compress() function. This new third option allows you to use "modifiers" to modify what compress() is doing. There are too many modifiers to list here, but they are worth looking up in the SAS V9 documentation.

Here is an example of a snippet of code I recently created to get rid of "non-printable" hex chars. This is a pretty standard data cleaning routine and is quite useful when some bad hex chars can creep into your text data. Instead of hunting and pecking for the funky hex chars you can just tell compress() to keep only the
"printable characters".

data _null_;
  x = 'A '  '16'x  'bad'  '18'x  ' sequence, with puncuation?';

  put x=;
  x = compress(x,,"kw");  * k is for keep, w is for "write-able";
  put x=;
run;

Notice in the compress() function there is no second parameter, and there is a new third parameter specified: "kw".
K is for keep, and W is for write-able. So this reads as keep only
a-zA-Zwhitespace0-9punctuation.

Pretty nice, eh?

As I said, there is a bunch of other modifiers available so take a look at the documentation. And happy coding!

Also, there are more examples of using the compress function with the optional third argument at my i-Doc site: http://idoc.pelicanprogramming.com/functions/COMPRESS.html

Hex It

Sometimes you need to specify an ASCII text character you can't see or print. You can specify any ASCII character using it's hex value and a hex literal in SAS. A hex literal in SAS is any of the 16 hex characters(0-9 and A-F) in quotes followed by an x. Such as '3A'x. You can see all the hex values for ASCII characters here: www.lookuptables.com

A classic example of this is creating a tab delimited file using a data _null_ step.

data _null_;
  set myData;
  put @01 var1 '09'x
      @10 var2 '09'x
  ;
run;

Another useful time to specify hex characters is to get rid of them. Suppose you
have some "dirty data" that somehow has some weird non-printable characters in it. You look at the text using the hex32 format and discover that some form feed characters somehow snuck into there (0x0C). The easiest way to get rid of them is to compress() the variable. Such as

myVar = compress(myVar,'0C'x); 

This will remove all occurrences of the character specified from the text variable.