COMPRESS Function
Returns a character string with specified characters removed from the original string.
| Categories: | Character |
| CAS | |
| Restriction: | This function is assigned an I18N Level 0 status, and is designed for SBCS data. Do not use this function to process DBCS or MBCS data. For more information, see Internationalization Compatibility. |
| Note: | This function supports the VARCHAR type. |
| Tip: | DBCS equivalent function is KCOMPRESS. |
Table of Contents
Syntax
Required Argument
source
specifies a character constant, variable, or expression from which specified characters are removed.
Optional Arguments
characters
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, form feed, and NBSP ('A0'x, or 160 decimal ASCII) 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.
Details
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:
|
Number of Arguments
|
Result
|
|---|---|
|
only the first argument, source
|
All blanks have been
removed from the argument. If the argument is completely blank, then
the result is a string with a length of zero. If you assign the result
to a character variable with a fixed length, then the value of that
variable will be padded with blanks to fill its defined length.
|
|
the first two arguments, source and chars
|
All characters that
appear in the second argument are removed from the result.
|
|
three arguments, source, chars,
and modifier(s)
|
The K modifier (specified
in the third argument) determines whether the characters in the second
argument are kept or removed from the result.
|
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");
Examples
Example 1: Compressing Blanks
The following SAS statements
produce this result:
|
SAS Statement
|
Result
|
|---|---|
|
|
----+----1 |
a='AB C D '; b=compress(a); put b; |
ABCD |
Example 2: Compressing Lowercase Letters
The following SAS statements
produce this result:
|
SAS Statement
|
Result
|
|---|---|
|
|
----+----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
The following SAS statements
produce this result:
|
SAS Statement
|
Result
|
|---|---|
|
|
----+----1 |
x='1 2 3 4 5'; y=compress(x, , 's'); put y; |
12345 |
Example 4: Keeping Characters in the List
The following SAS statements
produce this result:
|
SAS Statement
|
Result
|
|---|---|
|
|
----+----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
The following SAS statements
produce this result:
|
SAS Statement
|
Result
|
|---|---|
|
|
----+----1 |
x=' '; l=lengthn(compress(x)); put l; |
0 |
See Also
Copyright © SAS Institute Inc. All Rights Reserved.
Last updated: March 16, 2017