StringReplacer

Replaces substrings matching a string or regular expression in the string contained in the source attribute.  

Parameters

Attributes

This parameter specifies which attributes will have substrings replaced.

Mode

This parameter specifies whether the Text To Replace parameter specifies a regular expression or text pattern to search for.

Case Sensitive

• Yes: The transformer will perform case-sensitive substring matching.
• No: The transformer will perform case-insensitive substring matching.

Text to Replace

This parameter specifies the string or regular expression that will be replaced if it is found in an attribute value.

Replacement Text

The Replacement Text parameter specifies the substring that will replace instances of the Text To Replace parameter.

If replacement text contains \#, where # is a digit between 1 and 9, then it is replaced in the substitution with the portion of string that matched the n-th parenthesized subexpression of the regular expression.

Special character sequences can be used in both the Text to Replace and Replacement Text parameters.

If the Mode parameter is set to Replace Regular Expression, Advanced Regular Expressions (AREs) are supported. An ARE is one or more branches, separated by "|", matching anything that matches any of the branches.

This table lists the special characters:

Special Character	Description
|	separates "branches" (or choices)
*	a sequence of 0 or more matches of what precedes it
+	a sequence of 1 or more matches of what precedes it
?	a sequence of 0 or 1 matches of what precedes it
.	matches any single character
^	matches the start of the value
$	matches the end of the value
[ ]	enclose a set of character choices
( )	enclose a "subexpression"
a	any character can be listed to be matched

Characters can be expressed as regular characters but they can also include any number of control characters.

Special character sequences are interpreted as shown below:

Sequence	Description
Ctrl+Shift+h (^H)	Backspace (0x08)
Ctrl+Shift+l (^L)	Form feed (0x0c)
Ctrl+Shift+j (^J)	Newline (0x0a)
Ctrl+Shift+r (^M)	Carriage return (0x0d)
Ctrl+Shift+i (^I)	Tab (0x09)
Ctrl+Shift+k (^K)	Vertical tab (0x0b)

Defining Special Characters

You can define special characters through the Text Editors. Click Open Text Editor from the parameter menu:

Text Editor

Enter characters using the shortcuts from the table above.

Note: To see tab characters, click the Options menu on the bottom left and select Show Spaces/Tabs.

If Attribute Value Does Not Contain Text

Set Attribute Value To

If the Text To Replace parameter is not found, the attribute value will be set to the value specified by this parameter.

Examples

In this example, a pure substitution of text is made without any use of regular expression functionality. This is the simplest kind of substring replacement.

   Source String: Bobby

   Text to Find: obb

   Replacement Text: ill

   Use Regular Expression: no

   Case Sensitive: yes

   Result: Billy

In this example, a pattern matching zero or more ’b’ characters is replaced with nothing.

   Source String: Bobby

   Text to Find: b*

   Replacement Text:

   Use Regular Expression: yes

   Case Sensitive: yes

   Result: Boy

In this example, a pattern matching zero or more ’b’ characters followed by a y is duplicated in the result (prepended by hyphens)

   Source String: Bobby

   Text to Find: (b*y)

   Replacement Text: --\1-\1

   Use Regular Expression: yes

   Case Sensitive: yes

   Result: Bo--bby-bby

Related Transformers

See the StringSearcher transformer help for additional regular expression examples.

To replace pairs of substrings, use the StringPairReplacer transformer.

To search for regular expression matches in a string without doing any replacement, use the StringSearcher transformer.

Additional Resources

Test regular expressions with the Regular Expression Editor in the parameter menu.

For more information on regular expression syntax, see http://perldoc.perl.org/perlre.html#Regular-Expressions.

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Transformer Categories

Strings

Technical History

Associated FME function or factory: @Tcl2 (string map and regsub functions)

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