PRXMATCH Function

Searches for a pattern match and returns the position at which the pattern is found

Category: Character String Matching

Syntax

PRXMATCH ( regular-expression -id perl-regular-expression , source )

Arguments

position

specifies the numeric position in source at which the pattern begins. If no match is found, PRXMATCH returns a zero.

regular-expression-id

specifies a numeric pattern identifier that is returned by the PRXPARSE function.
Restriction: If you use this argument, you must also use the PRXPARSE function.

perl-regular-expression

specifies a Perl regular expression.

source

specifies the character expression that you want to search.

Details

The Basics If you use regular-expression-id , then the PRXMATCH function searches source with the regular-expression-id that is returned by PRXPARSE, and returns the position at which the string begins. If there is no match, PRXMATCH returns a zero.

If you use perl-regular-expression , PRXMATCH searches source with the perl-regular-expression , and you do not need to call PRXPARSE.

You can use PRXMATCH with a Perl regular expression in a WHERE clause and in PROC SQL. For more information about pattern matching, see 'Pattern Matching Using SAS Regular Expressions (RX) and Perl Regular Expressions (PRX)' on page 260.

Compiling a Perl Regular Expression If perl-regular-expression is a constant or if it uses the /o option, then the Perl regular expression is compiled once and each use of PRXMATCH reuses the compiled expression. If perl-regular-expression is not a constant and if it does not use the /o option, then the Perl regular expression is recompiled for each call to PRXMATCH.

Note: The compile-once behavior occurs when you use PRXMATCH in a DATA step, in a WHERE clause, or in PROC SQL. For all other uses, the perl-regular-expression is recompiled for each call to PRXMATCH.

Comparisons

The Perl regular expression (PRX) functions and CALL routines work together to manipulate strings that match patterns. To see a list and short description of these functions and CALL routines, see the Character String Matching category in 'Functions and CALL Routines by Category' on page 270.

Examples

Example 1: Finding the Position of a Substring in a String

Finding the Position of a Substring by Using PRXPARSE The following example searches a string for a substring, and returns its position in the string.

 data _null_;        /* Use PRXPARSE to compile the Perl regular expression.    */     patternID = prxparse('/world/');        /* Use PRXMATCH to find the position of the pattern match. */     position=prxmatch(patternID, 'Hello world!');     put position=;  run;

SAS writes the following line to the log:

 position=7

Finding the Position of a Substring by Using a Perl Regular Expression The following example uses a Perl regular expression to search a string (Hello world) for a substring (world) and to return the position of the substring in the string.

 data _null_;        /* Use PRXMATCH to find the position of the pattern match. */     position=prxmatch('/world/', 'Hello world!');     put position=;  run;

SAS writes the following line to the SAS:

 position=7

Example 2: Finding the Position of a Substring in a String-A Complex Example

The following example uses several Perl regular expression functions and a CALL routine to find the position of a substring in a string.

 data _null_;     if _N_ = 1 then     do;        retain PerlExpression;        pattern = "/(\d+):(\d\d)(?:\.(\d+))?/";        PerlExpression = prxparse(pattern);     end;     array match[3] $ 8;     input minsec .;     position = prxmatch(PerlExpression, minsec);     if position ^= 0 then     do;        do i = 1 to prxparen(PerlExpression);           call prxposn(PerlExpression, i, start, length);           if start ^= 0 then              match[i] = substr(minsec, start, length);        end;        put match[1] "minutes, " match[2] "seconds" @;        if ^missing(match[3]) then           put ", " match[3] "milliseconds";     end;     datalines;  14:56.456  45:32  ;  run;

The following lines are written to the SAS log:

 14 minutes, 56 seconds, 456 milliseconds  45 minutes, 32 seconds

Example 3: Extracting a Zip Code from a Data Set

Extracting a Zip Code by Using the DATA Step The following example uses a DATA step to search each observation in a data set for a nine-digit zip code, and writes those observations to the data set ZipPlus4.

 data ZipCodes;     input name: . zip:.;     datalines;  Johnathan 32523-2343  Seth 85030  Kim 39204  Samuel 93849-3843  ;     /* Extract ZIP+4 ZIP codes with the DATA step. */  data ZipPlus4;     set ZipCodes;     where prxmatch('/\d{5}-\d{4}/', zip);  run;  options nodate pageno=1 ls=80 ps=64;  proc print data=ZipPlus4;  run;

Output 4.37: Zip Code Output from the DATA Step

 The SAS System             1  Obs     name            zip   1      Johnathan    32523-2343   2      Samuel       93849-3843

Extracting a Zip Code by Using PROC SQL The following example searches each observation in a data set for a nine-digit zip code, and writes those observations to the data set ZipPlus4.

 data ZipCodes;     input name: . zip:.;     datalines;  Johnathan 32523-2343  Seth 85030  Kim 39204  Samuel 93849-3843  ;     /* Extract ZIP+4 ZIP codes with PROC SQL. */  proc sql;     create table ZipPlus4 as     select * from ZipCodes     where prxmatch('/\d{5}-\d{4}/', zip);  run;  options nodate pageno=1 ls=80 ps=64;  proc print data=ZipPlus4;  run;

Output 4.38: Zip Code Output from PROC SQL

 The SAS System             1  Obs     name            zip   1      Johnathan    32523-2343   2      Samuel       93849-3843

PRXMATCH Function