Scripting Guide - SAS

Chapter 6 Types of Data 125
Use Pattern Matching and Regular Expressions
1 2 1 2 1 2,
3 4 3 4 3 4]
repeat(9,2,3)
[ 9 9 9,
9 9 9]
The repeat function is compatible with the function of the same name in the SAS/IML language, but is
incompatible with the SAS character DATA step function, which repeats one more time than this function.
Use Pattern Matching and Regular Expressions
Pattern matching in JSL is a flexible method for searching and manipulating strings.
You define and use pattern variables just like any JMP variable:
i = 3; // a numeric variable
a = "Ralph"; // a character variable
t = textbox("Madge"); // a display box variable
p = ( "this" | "that" ) + patSpan(" ") + ( "car" | "bus" ); // a pattern
variable
When the above statement executes, p is assigned a pattern value. The pattern value can be used either to
construct another pattern or to perform a pattern match. The patSpan function returns a pattern that
matches a span of characters specified in the argument; patSpan("0123456789") matches runs of digits.
p2 = "Take " + p + "."; // using p to build another pattern
if( patMatch( "Take this bus.", p2 ), print("matches"), print("no match") ); /
/ performing a match
Sometime all you need to know is that the pattern matched the source text, as above. Other times, you
might want to know what matched; for example, was it a bus or a car?
p = ( "this" | "that" ) + patSpan(" ") + ( "car" | "bus" ) >? vehicleType; //
conditional assignment ONLY if pattern matches
if( patMatch( "Take this bus.", p ), show(vehicleType), print("no match") ); /
/ do not use vehicleType in the ELSE because it is not set
You could pre-load vehicleType with a default value if you do not want to check the outcome of the
match with an if. The >? conditional assignment operator has two arguments, the first being a pattern and
the second a JSL variable. >? constructs a pattern that matches the pattern (first argument) and stores the
result of the match in the JSL variable (second argument) after the pattern succeeds. Similarly, >> does not
wait for the pattern to succeed. As soon (and as often) as the >> pattern matches, the assignment is
performed.
findDelimString = patLen(3)>>beginDelim + patArb()>?middlePart +
expr(beginDelim);
testString = "SomeoneSawTheQuickBrownFoxJumpOverTheLazyDog'sBack";
rc = PatMatch( testString, findDelimString, "" );
show( rc, beginDelim, middlePart, testString );
The above example shows a third argument in the patMatch function: the replacement string. In this case,
the replacement is formed from a concatenation (|| operator) of three strings. One of the three strings,