List of Transformers

You are here: Attributes > ListBuilder

ListBuilder

Combines attributes of the input features into a single list structure.

Output Ports

One feature is output for each unique combination of values of the attributes specified in the Group By parameter. Features output from this transformer have no geometry.

Parameters

Transformer

ClosedGroup By

This parameter allows you to specify the attribute values on which to join the series of input features. One feature is output for each group created by selecting a Group By attribute. If no Group By attributes are specified, then a single feature is output and the number of elements in its list is equivalent to the number of features input into the ListBuilder.

ClosedParallel Processing

Note: How parallel processing works with FME: see About Parallel Processing for detailed information.

This parameter determines whether or not the transformer should perform the work across parallel processes. If it is enabled, a process will be launched for each group specified by the Group By parameter.

Parallel Processing Levels

Parameter Number of Processes
No Parallelism 1
Minimal coresThe processor, or CPU, is the physical part of the computer that performs mathematical calculations. It is the most important part of a computer system. Traditional processors have only one core on the processor, meaning that at any given time, only one set of calculations is being performed. If a processor is dual-core, this means the single chip contains hardware for two processors, now called cores to distinguish them from the single chip, running simultaneously, side by side. (Source: http://www.ehow.com/facts_5730257_computer-core-processors_.html) / 2
Moderate exact number of cores
Aggressive cores x 1.5
Extreme cores x 2

For example, on a quad-core machine, minimal parallelism will result in two simultaneous FME processes. Extreme parallelism on an 8-core machine would result in 16 simultaneous processes.

You can experiment with this feature and view the information in the Windows Task Manager and the Workbench Log window.

ClosedInput Ordered

No: This is the default behavior. Processing will only occur in this transformer once all input is present.

By Group: This transformer will process input groups in order. Changes on the value of the Group By parameter on the input stream will trigger batch processing on the currently accumulating group. This will improve overall speed if groups are large/complex, but could cause undesired behavior if input groups are not truly ordered.

Parameters

ClosedList Name

The features output from the ListBuilder have all of their attributes stored in the list identified by the name specified by this parameter.

Example

Suppose this transformer is used with no group-by attributes, and three features enter it with these attributes:

 Feature 0:

length = 7.3

kind = 'paved'

Feature 1:

length = 8.4

kind = ’smooth’

lanes = 2

Feature 2: 

length = 1.1

 kind = ’rough’

then, presuming that the list name specified was somelist, a single feature with these attributes is output:

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’

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

Attributes

Search FME Knowledge Center

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