ListExploder

Explodes each list member on each input feature out into its own feature.

Any attributes on the list are copied to become non-list attributes of the feature output. In addition, the element number of the attributes in the original list is added to the feature. Each feature's output has a copy of the geometry from the original input feature.

If Input attributes and list element attributes have the same name, the Input attributes will be overwritten by the list element attributes.
ListExploder will not work with an invalid list, such as one that doesn't start at entry 0. For example:

Valid List	Invalid List
mylist{0}.attr1	mylist{1}.attr1
mylist{1}.attr1	mylist{2}.attr1
mylist{2}.attr1	mylist{3}.attr1
mylist{3}.attr1	mylist{4}.attr1

Examples

Example 1

If this feature enters this transformer:

somelist{0}.length = 7.3

somelist{0}.kind = ’paved’

somelist{1}.length = 8.4

somelist{1}.kind = ’smooth’

somelist{1}.lanes = 2

somelist{2}.length = 1.1

somelist{2}.kind = ’rough’

another_attr = ’something else’

then, presuming that the list name specified was somelist{}, the index attribute was element_num, and the Accumulation Mode parameter was set to Merge List Attributes, the first returned feature would look like:

length = 7.3

kind = ’paved’

element_num = 0

another_attr = ’something else’

If the Accumulation Mode parameter was set to Only Use List Attributes, the first returned feature would look like:

length = 7.3

kind = ’paved’

element_num = 0

Example 2

Suppose you have a Input feature with the following 6 attributes. (The List Attribute used here would be ID{}.)

Name

Type

ID{0}.dec

ID{0}.hex

ID{1}.dec

ID{1}.hex

Merge List Attributes will produce elements with 4 attributes:

Name

Type

dec

hex

Only Use List Attributes will produce elements with 2 attributes:

dec

hex

Configuration

Input Ports

Output Ports

Parameters

Attribute Accumulation

Accumulation Mode

Merge List Attributes: The feature retains all of its own un-conflicted attributes, and additionally acquires any un-conflicted attributes generated by the transformer. This mode handles conflicted attributes according to the Conflict Resolution parameter.

Prefix List Attributes: The feature retains all of its own attributes. In addition, the feature acquires attributes generated by the transformer, with the name prefixed with the Prefix parameter.

Only Use List Attributes: All of the feature's attributes are removed, except geometry attributes that start with fme_. Then, the feature acquires all of the attributes and associated values that are generated from the exploded list attribute.

Conflict Resolution

Use Original Attribute Values: If a conflict occurs, maintain the values of the original, non-list attribute.

Use List Attribute Values: If a conflict occurs, transfer the values of the generated attributes onto the original, non-list attributes.

Prefix

If the Accumulation Mode parameter is set to Prefix List Attributes, this value prefixes attributes that are added to the feature.

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.

FME Community

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