FME Transformers: 2024.2

Categories
Calculated Values

Calculated Values

Spatial Analysis

Spatial Analysis

Categories
Calculated Values

Calculated Values

Spatial Analysis

Spatial Analysis

NetworkCostCalculator

Computes and assigns the cost of the shortest path from a source object to each connected object as the Z-values or measure values of the input features.

Configuration

Input Ports

Network lines.

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.

There can only be one Source input for each group.

Output Ports

All lines that are connected to the Source input port are output through the Connected port.

The lines that are not connected to the Source input port will be output through the Disconnected port. If Output Optimal Cost As parameter is set to Z-Values, the dimension of the disconnected lines is set to 2D. Otherwise, disconnected lines are untouched.

There can only be one Source input for each group. All other inputs and non-linear features are output through the <Rejected> port.

Parameters

Group By

Choose the attributes to group by.

Complete Groups

Select the point in processing at which groups are processed:

When All Features Received

This is the default behavior. Processing will only occur in this transformer once all input is present.

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 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 When All Features Received 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.

Weight Type, Forward Weight Attribute, Reverse Weight Attribute

If Weight Type is set to By Length (Forward Only) or By One Attribute, then the weight of each input line is set to the length of the line or the attribute value specified in the Forward Weight Attribute. In this case, the algorithm will only consider the original orientation of the lines when computing the cost of the shortest path.

If Weight Type is set to By Length or By Two Attributes, then the shortest path algorithm will consider both directions of the input lines. If Weight Type is set to By Two Attributes, the original orientation of the input line has the weight specified in the Forward Weight Attribute and the reversed orientation of the input line has the weight specified in the Reverse Weight Attribute. If Weight Type is set to By Length, the weight of both the original orientation and the reversed orientation of the input line is set to the length of the line.

Only linear features with non-negative weight attribute values are allowed if the Weight Type is set to By One Attribute or By Two Attributes. If a feature does not have the attribute specified in the Forward Weight Attribute or the Reverse Weight Attribute, a zero weight is used for the line.

Output Optimal Cost As

If this parameter is set to Z-Values, then the optimal cost for each connected node is set as the Z-value of the node. Otherwise, the optimal cost is set as the measure value of the node with the measure name specified in Measure Name.

Measure Name

If you leave the Measure Name empty, the default measure name will be used.

Snap Source Points/Snapping Tolerance

If this parameter is set to Yes, the transformer snaps the source points to the closest end points of the network lines.

The source points are only snapped to the network lines if they are within the tolerance specified in Snapping Tolerance.

See Geometry Concepts > Tolerance.

Preserve Feature Order

This parameter controls the order in which features exit a transformer.

When a transformer has more than one output port, features usually exit one port at a time. At times, it may be useful to keep the order that features arrived in, switching from port to port as necessary. This allows feature order to be preserved, though at a potential cost in processing efficiency.

Select a method for feature ordering.

Per Output Port (Default)

Only preserve the input order of features as they occur within the group of features exiting a given output port.

All features exiting an output port retain their ordering relative to each other (within the group), but not relative to features exiting other output ports.

This option is generally the most efficient, where large chunks of features will exit an output port together (taking advantage of bulk mode).

As features exiting different output ports may not be strictly output in the order they arrived, output ordering may be unpredictable.

Across Output Ports

Strictly preserve the input order of features, regardless of which output port they exit. Features will be output singly in the same order they arrived, switching from port to port as necessary. This option is generally less efficient as the processing gains of bulk mode are less likely to apply - however, feature order is predictable.

Editing Transformer Parameters

Transformer parameters can be set by directly entering values, using expressions, or referencing other elements in the workspace such as attribute values or user parameters. Various editors and context menus are available to assist. To see what is available, click beside the applicable parameter.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters.

Using the Text Editor

The Text Editor provides a convenient way to construct text strings (including regular expressions) from various data sources, such as attributes, parameters, and constants, where the result is used directly inside a parameter.

Text Editor

Using the Arithmetic Editor

The Arithmetic Editor provides a convenient way to construct math expressions from various data sources, such as attributes, parameters, and feature functions, where the result is used directly inside a parameter.

Arithmetic Editor

Conditional Values

Set values depending on one or more test conditions that either pass or fail.

Parameter Condition Definition Dialog

Content

Expressions and strings can include a number of functions, characters, parameters, and more.

When setting values - whether entered directly in a parameter or constructed using one of the editors - strings and expressions containing String, Math, Date/Time or FME Feature Functions will have those functions evaluated. Therefore, the names of these functions (in the form @<function_name>) should not be used as literal string values.

String Functions

These functions manipulate and format strings.

Special Characters

 A set of control characters is available in the Text Editor.

Math Functions

Math functions are available in both editors.
Date/Time Functions Date and time functions are available in the Text Editor.

Math Operators

These operators are available in the Arithmetic Editor.

FME Feature Functions

These return primarily feature-specific values.

FME Parameters

FME and workspace-specific parameters may be used.
Creating and Modifying User Parameters Create your own editable parameters.

Table Tools

Transformers with table-style parameters have additional tools for populating and manipulating values.

Row Reordering

Enabled once you have clicked on a row item. Choices include:

  • Add a row
  • Remove a row
  • Move current row up one
  • Move current row down one
  • Move current row to top
  • Move current row to bottom

Cut, Copy, and Paste

Enabled once you have clicked on a row item. Choices include:

  • Cut a row - delete and copy to clipboard
  • Copy a row to the clipboard
  • Paste a row from the clipboard

Cut, copy, and paste may be used within a transformer, or between transformers.

Filter

Start typing a string, and the matrix will only display rows matching those characters. Searches all columns. This only affects the display of attributes within the transformer - it does not alter which attributes are output.

Import

Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers.

Reset/Refresh

Generally resets the table to its initial state, and may provide additional options to remove invalid entries. Behavior varies between transformers.

Note: Not all tools are available in all transformers.

For more information, see Transformer Parameter Menu Options.

FME Community

The FME Community has a wealth of FME knowledge with over 20,000 active members worldwide. Get help with FME, share knowledge, and connect with users globally.

Search for all results about the NetworkCostCalculator on the FME Community.

Keywords: topology