SubstringExtractor

Categories

Calculated Values

Strings

Extracts a substring from the source attribute. The substring is taken from the range of characters specified.

Parameters

Specify the attribute or other source for the string from which you want to extract a substring.

 Specify the position in the source string from which to begin extracting a substring, and the position in the source string to end the substring. Character indexes start at 0 for the first character.  A negative index is used to indicate the position relative to the end of the string (-1 is the last character, -2 the second last, and so on).

If the last index is greater than or equal to the length of the string, then it is treated as if it were the end of the string. If the first index is greater than the last index, then an empty string is placed into the result attribute.

The index parameters may be entered as a number, or can be taken from the value of a feature attribute by selecting the attribute name from the pull-down list.

Specify a name for the attribute that holds the substring.

Examples

  • To trim off the first character only, and extract the rest of the source string, use a start of 1 and an end of -1.
  • To trim off the last character only, and extract the rest of the source string, use a start of 0 and an end of -2.
  • To extract the second and third characters in the string, use a start of 1 and an end of 2.
  • To trim off a single character only, use a start of 4 and an end of 4.
  • If you want to split the four first characters of the string ABCDE, use four SubstringExtractor transformers and set their respective properties as follows:

0,0

1,1

2,2

3,3

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.

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. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

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.

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

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.

FME Community

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Search for samples and information about this transformer on the FME Community.