COMPRESS Function

Arguments

source

specifies a character constant, variable, or expression from which specified characters will be removed.

chars

specifies a character constant, variable, or expression that initializes a list of characters.

By default, the characters in this list are removed from the source argument. If you specify the K modifier in the third argument, then only the characters in this list are kept in the result.

Tip:	You can add more characters to this list by using other modifiers in the third argument.
Tip:	Enclose a literal string of characters in quotation marks.

modifier

specifies a character constant, variable, or expression in which each non-blank character modifies the action of the COMPRESS function. Blanks are ignored. The following characters can be used as modifiers:

a or A	adds alphabetic characters to the list of characters.
c or C	adds control characters to the list of characters.
d or D	adds digits to the list of characters.
f or F	adds the underscore character and English letters to the list of characters.
g or G	adds graphic characters to the list of characters.
h or H	adds a horizontal tab to the list of characters.
i or I	ignores the case of the characters to be kept or removed.
k or K	keeps the characters in the list instead of removing them.
l or L	adds lowercase letters to the list of characters.
n or N	adds digits, the underscore character, and English letters to the list of characters.
o or O	processes the second and third arguments once rather than every time the COMPRESS function is called. Using the O modifier in the DATA step (excluding WHERE clauses), or in the SQL procedure, can make COMPRESS run much faster when you call it in a loop where the second and third arguments do not change.
p or P	adds punctuation marks to the list of characters.
s or S	adds space characters (blank, horizontal tab, vertical tab, carriage return, line feed, and form feed) to the list of characters.
t or T	trims trailing blanks from the first and second arguments.
u or U	adds uppercase letters to the list of characters.
w or W	adds printable characters to the list of characters.
x or X	adds hexadecimal characters to the list of characters.

Tip:	If the modifier is a constant, enclose it in quotation marks. Specify multiple constants in a single set of quotation marks. Modifier can also be expressed as a variable or an expression.

Length of Returned Variable

In a DATA step, if the COMPRESS function returns a value to a variable that has not previously been assigned a length, then that variable is given the length of the first argument.

The Basics

The COMPRESS function allows null arguments. A null argument is treated as a string that has a length of zero.

Based on the number of arguments, the COMPRESS functions works as follows:

The COMPRESS function compiles a list of characters to keep or remove, comprising the characters in the second argument plus any types of characters that are specified by the modifiers. For example, the D modifier specifies digits. Both of the following function calls remove digits from the result:

COMPRESS(source, "1234567890");
COMPRESS(source, , "d");

To remove digits and plus or minus signs, you can use either of the following function calls:

COMPRESS(source, "1234567890+-");
COMPRESS(source, "+-", "d");

Example 1: Compressing Blanks

----+----1

a='AB C D ';
b=compress(a);
put b;

 

ABCD

Example 2: Compressing Lowercase Letters

----+----1----+----2----+----3

x='123-4567-8901 B 234-5678-9012 c';
y=compress(x,'ABCD','l');
put y;

  

123-4567-8901 234-5678-9012

Example 3: Compressing Space Characters

----+----1

x='1    2    3    4    5';
y=compress(x,,'s');
put y;

 

12345

Example 4: Keeping Characters in the List

----+----1

x='Math A English B Physics A';
y=compress(x,'ABCD','k');
put y;

 

ABA

Example 5: Compressing a String and Returning a Length of 0

----+----1

x=' ';
l=lengthn(compress(x));
put l;

 

0

Copyright © 2011 by SAS Institute Inc., Cary, NC, USA. All rights reserved.