ShortestPathFinder

Lines defining the network in which to find a path or paths.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.

TheFrom-Toline contains vertices that define the source and destination nodes in the network.It can contain intermediate stops before the final destination.For example,aFrom-Toline may be used to find the path from A to B to C to D.This can also be read as "the path from A to D that also passes through B and C."From-Tolines can be created by connecting points together to form a line,using thePointConnectororVertexCreatortransformers.

For eachFrom-Toline,if a path is found it will be output as a single feature through thePathport.This output feature contains the attributes and coordinate system of the originalFrom-Toline.The geometry of the output feature is made up of all the parts of network that form the shortest path.Note that ifCost Typeis set toBy One AttributeorBy Two Attributesthen the "shortest path" is the one where the sum of the values of the applicableCost Attributevalues is the least.

If a path is not found for a givenFrom-Toline,then thisFrom-Toline will be output through theNoPathport as a feature that preserves the originalFrom-Toattributes but has no geometry.

All network features that are not used as part of the shortest path are output through theUnusedport.

InputFrom-Tolines that are reordered using parameters under Optimization Options are output through this port.

All non-linear features from either input port are output through the port,as are anyFrom-Tolines that have a negative cost (whenCost Typeis set toBy One AttributeorBy Two Attributes).

Rejected features will have anfme_rejection_codeattribute with one of the following values:INVALID_DESTINATION_GEOMETRY_TYPE,INVALID_LINE_GEOMETRY_TYPE,INVALID_PARAMETER_WEIGHT.

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.You can select attributes from bothNetworkandFrom-Toinput features.

Note:How parallel processing works with FME: seeAbout Parallel Processingfor detailed information.

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

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 theGroup Byparameter 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.

IfCost Typeis set toBy LengthorBy One Attribute,then the cost of each input line is set to the length of the line or the attribute value specified in theForward Cost Attribute.In this case,the algorithm will only consider the original orientation of the lines when finding the shortest path.

IfCost Typeis set toBy Two Attributes,then the shortest path algorithm will consider both directions of the input lines.The original orientation of the input line has the cost specified in theForward Cost Attributeand the reversed orientation of the input line has the cost specified in theReverse Cost Attribute.

The values that result fromCost Typeare summed for all input lines as they relate to theFrom-Toline,and the shortest sum becomes the shortest-found path.

This parameter is used whenCost Typeis set toBy One AttributeorBy Two Attributes.

This parameter is used whenCost Typeis set toBy Two Attributes.

When specified,this attribute list that will hold the attributes for each inputNetworkfeature that make upPathoutput features.

This list also contains a_directionattribute that stores the direction of the segment of the shortest path as compared to its originalNetworkfeature.It will either be "same" or "opposite",depending if the originalNetworkfeature had to be reversed or not.

SelectYesto snap the points of theFrom-Toline to the closest end points of theNetworklines.The points are only snapped to the network lines if they are within the tolerance specified inSnapping Tolerance.

Note:The shortest distance is calculated based on the specifiedFrom-Toline and is not affected by snapping.

The tolerance used whenFrom-To and Network Snappingis set toYes.Points of theFrom-Toline will be snapped to theNetworklines if they are within this tolerance.

Specifies whether the points of the inputFrom-Toline should be reordered to find a shorter path.This option is useful when the order of points of theFrom-Toline is not important,such as in travelling salesman problems.A metaheuristic is used to find a low-cost ordering of points.

No: The inputFrom-Toline is used as-is.No optimization occurs.

Intermediate Points Only: The start and end points of the inputFrom-Toline are untouched.Intermediate points are reordered.

All Points: All points of the inputFrom-Toline are reordered.

The number of times to run the optimization algorithm.The greater the number of iterations,the closer the result will be to the optimal solution.Increasing this parameter increases translation time.

This parameter must be set to a positive integer.The default value is 10000.

The number of times the optimization algorithm needs to return the same potential result before it is accepted.Setting this parameter to a high value may result in very long translation time or cause the translation to never complete.

This parameter must be set to a non-negative integer.A value of 0 specifies that no verifications are required.The default value is 1.

The greatest cost that will be accepted as valid.Setting this parameter to a low value may cause the translation to never complete.

This parameter must be set to a non-negative value.A value of 0 specifies that there is no restriction on the cost that will be accepted.The default value is 0.