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
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.
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
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.
Yes: 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.
No: This is the default behavior. Processing will only occur in this transformer once all input is present.
Parameters
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
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Search for samples and information about this transformer on the FME Knowledge Center.