Fixes the flow (direction) of each edge or linear feature in the network to fit the downstream direction to the destination node.
Input Line features must be a topologically noded network with features connecting at line ends only. That is, all features must be split at junctions.
Only one destination node is allowed for each group.
All connected features are output through the Network port.
All edges or linear features not connected to the destination node are output through the Unused port.
All non-linear features or extra destination nodes are output through the <Rejected> port.
The default behavior is to use the entire set of features as the group. This option allows you to select attributes that define which groups to form.
Process At End (Blocking): This is the default behavior. Processing will only occur in this transformer once all input is present.
Process When Group Changes (Advanced): This transformer will process input groups in order. Changes of the value of the Group By parameter on the input stream will trigger processing on the currently accumulating group. This may improve overall speed (particularly with multiple, equally-sized groups), but could cause undesired behavior if input groups are not truly ordered.
There are two typical reasons for using Process When Group Changes (Advanced) . The first is incoming data that is intended to be processed in groups (and is already so ordered). In this case, the structure dictates Group By usage - not performance considerations.
The second possible reason is potential performance gains.
Performance gains are most likely when the data is already sorted (or read using a SQL ORDER BY statement) since less work is required of FME. If the data needs ordering, it can be sorted in the workspace (though the added processing overhead may negate any gains).
Sorting becomes more difficult according to the number of data streams. Multiple streams of data could be almost impossible to sort into the correct order, since all features matching a Group By value need to arrive before any features (of any feature type or dataset) belonging to the next group. In this case, using Group By with Process At End (Blocking) may be the equivalent and simpler approach.
Note: Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.
As with many scenarios, testing different approaches in your workspace with your data is the only definitive way to identify performance gains.
If an edge is reversed, the value of the attribute specified in Direction Attribute will be opposite. Otherwise, the value will be same.
The functionality works well in a non-cycle network; however, it does not always yield desired results in a cycle network. One way to fix a cycle network is to omit edges that should not be modified from the input.
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.
FME Licensing Level
FME Professional edition and above
FME Factory Used: NetworkFactory
Search FME Community
Search for samples and information about this transformer on the FME Community.
Tags Keywords: NetworkFlowSetter