StringReplacer

Replaces substrings matching text or patterns described by regular expressions.

Typical Uses

Editing strings based on text or pattern matching

How does it work?

The StringReplacer receives features with attributes and replaces portions of attribute values (substrings) with new text.

Replacement can be done either by matching a specific string or by using regular expressions to specify string patterns. Matching may be case-sensitive or not.

Multiple replacements can be performed in a single StringReplacer. They are executed sequentially, and so can operate on earlier replacements done in the same transformer.

Matching Text

When Mode is Replace Text, the input string is matched exactly (with the option of case-sensitivity) and replaced.

Input	Text to Replace	Replacement Text	Output
Bobby	obb	ill	Billy

Matching Regular Expressions

When Mode is Replace Regular Expression, input strings are evaluated against a regular expression.

Input	Text to Replace	Replacement Text	Output
Look_cows	o{2}	88	L88k_cows

Regular expressions can be created and tested in the Regular Expression Editor, accessible via the Text to Replace context menu.

Special characters and sequences are used, some of which are listed here:

Special Character	Description
\|	Separates branches (choices)
*	Match 0 or more times
+	Match 1 or more times
?	Match 1 or 0 times
.	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"

Advanced Regular Expressions (AREs) are supported. AREs have one or more branches, separated by |, matching any of the branches.

Note For full information on syntax, special characters, and more, see Perldoc - Regular Expressions.

Using Match Groups

Match groups are created when sub-parts exist in the expression, enclosed in parentheses. Each part captures a sub-match from the input text.

These parts can be referred to in the Replacement Text by a backslash followed by the number of the part - \2 refers to the contents matching the second set of parentheses.

In this example, the expression describes a pattern of a word, then a space, then a second word. The words are enclosed in parentheses, and so can be used as a match group.

In the StringReplacer, it could be used like this:

Input	Text to Replace	Replacement Text	Output
First Second	(\w+)\s(\w+)	\2 \1	Second First

Usage Notes

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

Configuration

Input Ports

Output Ports

Parameters

Comparison

Mode

Select a method of specifying strings to be replaced:

Replace Text: Find text matching an exact string.
Replace Regular Expression: Find text matching a pattern.

Case Sensitive

Select an option for case-sensitivity when finding strings or patterns:

Yes: Match exactly.
No: Disregard case when matching.

Replace Strings

This table specifies the replacements to be done and the order in which to execute them.

Each row defines one string replacement.

Attribute	Specify the attribute containing the value to be revised.
Text to Replace	Specify the string or regular expression to match.
Replacement Text	Specify the new string to replace any occurrences of the Text to Replace.

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

How to Set Parameter Values

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

Content Types

String Functions	These functions manipulate and format strings.
Special Characters	A set of control characters is available in the Text Editor.
Math Functions	Math functions are available in both editors.
Date/Time Functions	Date and time functions are available in the Text Editor.
Math Operators	These operators are available in the Arithmetic Editor.
FME Feature Functions	These return primarily feature-specific values.
FME Parameters	FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters	Create your own editable parameters.

Dialog Options - Tables

Table Tools

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

Add a row
Remove a row
Move current row up one
Move current row down one
Move current row to top
Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

Cut a row - delete and copy to clipboard
Copy a row to the clipboard
Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

For more information, see Transformer Parameter Menu Options.

Reference

Processing Behavior	Feature-Based
Feature Holding	No
Dependencies	None
Aliases
History

FME Online Resources

The FME Community and Support Center Knowledge Base have a wealth of information, including active forums with 35,000+ members and thousands of articles.

Search for all results about the StringReplacer on the FME Community.

Examples may contain information licensed under the Open Government Licence – Vancouver, Open Government Licence - British Columbia, and/or Open Government Licence – Canada.