NeighborFinder

If a Candidate feature is found, then all the attributes from the closest Candidate feature are added to the Base feature and the Base feature is output via the Matched port. In addition, several other attributes are added to the Base feature just prior to it being output via the Matched port:

If there are no Candidate features found to be within the maximum distance, then the Base feature will be output unchanged via the UnmatchedBase port.

Candidate features not within the Maximum Distance to any Base feature are output via the UnmatchedCandidate port. Also, if no Close Candidate List Name is specified, then any features within the Maximum Distance, but not closest, will be output from the UnmatchedCandidate port. This is because they are not used in any way; their attributes are not merged onto the base at all.

Invalid features are output via the <Rejected> port. Base and candidate features with null geometry will be rejected. Features with invalid geometries may also be rejected.

Rejected features will have an fme_rejection_code attribute with one of the following values: EXTRA_CANDIDATE_FEATURE, INVALID_BASE_GEOMETRY_VERTICES, INVALID_CANDIDATE_GEOMETRY_VERTICES, INVALID_GEOMETRY_VERTICES.

The default behavior is to use the entire set of input features as the group. This option allows you to select attributes that define which groups to form. Each set of features that have the same value for all of these attributes will be processed as an independent group.

If Input is set to Bases and Candidates, then the transformer will have a Base port as well as a Candidate port, and the transformer will look for the Candidate feature that lies closest to each Base feature. If Input is set to Candidates Only, then the transformer will have only a Candidate port and no Base port. Each Candidate will then also act as a Base.

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.

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. Specifically, on a two input-port transformer, "in order" means that an entire group must reach both ports before the next group reaches either port, for the transformer to work as expected. This may take careful consideration in a workspace, and should not be confused with both port's input streams being ordered individually, but not synchronously.

The maximum number of candidate features that will be included in the list specified by the Close Candidate List Name parameter. The closest candidate features will be included in the list.

A value must be specified for at least one of the Number of Neighbors to Find and Maximum Distance parameters.

The maximum distance is measured in the units of coordinates of the input features.

The list specified in the Close Candidate List Name contains all of the candidate features that were within the maximum distance of the base. Candidates exactly at the maximum distance will be included in the Close Candidate List.

A value must be specified for at least one of the Number of Neighbors to Find and Maximum Distance parameters.

Note: To get the distance from a given Base to all Candidate features, use a very large number for this parameter and specify a Close Candidate List Name.

If Insert Vertex On Base Feature is Yes, then (_closest_base_x, _closest_base_y) will be inserted onto the Base feature if the insertion is well-defined. For example, if a Candidate polygon is contained inside a Base polygon, insertion will not take place.

If Insert Vertex On Base Feature is Yes, the _closest_base_x, _closest_base_y vertex will be inserted onto to the Base feature as well as added as an attribute. This option only applies to Lines, Polygons, Paths, Arcs, Ellipses, and Donuts.

If set to Yes, then all Candidate features must be input before any Base features. If a Candidate feature is input after a Base feature and this option is set to Yes, the Candidate feature will be ignored in all calculations.

If specified, a list will be built on the Matched output, consisting of all the attributes from the Candidate features that were within maximum distance of the Base feature.

Note: List attributes are not accessible from the output schema in Workbench unless they are first processed using a transformer that operates on them, such as ListExploder or ListConcatenator. All list attribute transformers are displayed in the Contents pane of the Transformer Help under Lists. Alternatively, AttributeExposer can be used.

• Lines: A polygon, donut, or ellipse will be treated as a line (that is, its boundary line) for backwards compatibility.
• Areas: A polygon, donut, or ellipse will be treated as an area, and any geometry that overlaps with the area will be of 0 distance away from that area.

If the candidate is a line, and the base is a point, this will specify if measures and z values should be copied from the candidate to the base. The measures and z value will be equal to the interpolated measures and z values at the point on the candidate that is closest to the base. If the candidate is not a line, or the base is not a point, this will have no effect.

If measures are being taken from the candidate, they can be treated as Discrete, meaning that they will be taken from the nearest known measure value on the candidate, or Continuous, meaning that they will be interpolated at the point along the candidate that is nearest to the base.

Merge Candidate: The base feature will retain all of its own un-conflicted attributes, and will additionally acquire any un-conflicted attributes that the candidate feature has. This mode will handle conflicted attributes based on the Conflict Resolution parameter.

Prefix Candidate: The base feature will retain all of its own attributes. In addition, the base will acquire attributes reflecting the candidate feature’s attributes, with the name prefixed with the Prefix parameter.

Only Use Candidate: The base feature will have all of its attributes removed, except geometry attributes that start with fme_. Then, all of the attributes from one (arbitrary) candidate feature will be placed onto the base.

Use Base: If a conflict occurs, the base values will be maintained.

Use Candidate: If a conflict occurs, the values of the candidate will be transferred onto the base.

To prevent a Candidate attribute from being ignored because the Base attribute already exists, you can optionally specify a prefix that will be applied to each Candidate attribute when it is added to the Base. This parameter is only enabled when the Accumulation Mode is Prefix Candidate.