NeighborPairFinder

Categories

Spatial Analysis

Finds the closest two Candidate features within some maximum distance of each Base feature and some minimum separation in heading between the Candidates and the Base.

Parameters

Specify the maximum distance from each Base feature within which to find the closest two Candidate features. The maximum distance is measured in the units of coordinates of the input features.

Minimum separation angle is measured in degrees, and specifies the minimum difference in heading from the base that the two candidates must have before the second one will be used.

Used to select a Candidate attribute from the two closest Candidates that will be preserved on the Base feature as _key attributes.

Usage Notes

If no, or only one, Candidate feature is found to be within the maximum distance, then the Base feature will be output unchanged via the UnmatchedBase port.

If two Candidates are found, then the Base feature is output via the MatchedBase port.  In this case, the following attributes will be added to the Base feature:

  • _distance1, _distance2 – The distance (in ground units) from the Base to the matching Candidate
  • _heading1, _heading2 – The angle between the closest interpolated Base point and the closest interpolated Candidate point.
  •  _closest_base_x1, _closest_base_y1, _closest_base_x2, _closest_base_y2 – The coordinates of the closest interpolated point on the Base feature to the closest interpolated point on the Candidate feature.
  • _closest_candidate_x1, _closest_candidate_y1, _closest_candidate_x2, _closest_candidate_y2 – The coordinates of the closest interpolated point on the Candidate feature to the closest interpolated point on the Base feature.
  • _candidate_angle1, _candidate_angle2 – The angle from the closest interpolated point on the Candidate feature to the next vertex within the Candidate feature.  (If the closest interpolated point on the Candidate feature is its last vertex, then candidate_angle will contain the angle from the previous vertex of the candidate feature to the closest interpolated point on the Candidate feature.)
  •  _candidate_label_angle1, _candidate_label_angle2 – The _candidate_angle adjusted so that if it is used as a text rotation, the text will run from left to right.  This angle is guaranteed to be greater than or equal to 270 and less than 360, or greater than or equal to 0 and less than or equal to 90.

(The attributes ending in 1 relate to the closest Candidate feature found.  The attributes ending in 2 relate to the next closest Candidate feature found, which has a sufficiently different heading.)

All headings are measured in degrees counterclockwise from horizontal.  All distances are measured in the ground units of the features.

The ClosestVector and SecondClosestVector ports will have linear features output on them that connect the closest points on the base and candidate features.  These ports are useful only for visualizing where the closest points were found.

Invalid features (such as extra candidates) are output via the <Rejected> port. Base and candidate features with null geometries will 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.

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.

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. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

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.

Dialog Options - Tables

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.

FME Licensing Level

FME Professional edition and above

FME Community

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Keywords: NeighbourPairFinder