Chopper

Breaks input features into points, lines, or areas. Chopped features contain the same set of vertices as input features.

This is useful when outputting to a format that has limitations on the number of coordinates in each feature. It can also be used to crudely simplify complex objects.

All new features have the same attributes as the original feature had and are output via the Output port. The optional chopping indicator attribute can be used to distinguish output features which were chopped from output features which were not.

Example

Usage Notes

Input arcs are stroked prior to chopping. If the chopping operation does not modify a stroked arc, the arc is unstroked and will be output untouched.
Area features are chopped in such a way as to preserve the original area of the feature. That is, the original area feature is cut into smaller areas, which if dissolved together, would match the original area. New vertices may be introduced into the area feature as it is chopped.

Configuration

Input Ports

Output Ports

Parameters

General

Mode	By Vertex: Breaks input features according to vertex count. Output geometries may be points, lines, or areas. By Length: Breaks input features according to length. Output geometries will consist of lines or areas.
Maximum Vertices	Each Output feature will have up to the specified number of vertices. For example, if an input line consists of 4 vertices, and a Maximum Vertices of 3 is specified, two Output lines would be output: one with 3 vertices and one with 2 vertices. If this parameter is less than 4, input area features are converted to linear features. If it is set to 1, all input features are broken up into point features.
Approximate Length	Each Output line feature will be a line feature whose length is close to the value specified in this parameter. Whenever two input vertices may represent the endpoint of an Output line feature, FME chooses the one that results in a length closer to the value of Approximate Length. For example, if a horizontal line consists of two segments of length 0.8, and you specify 1 for Approximate Length, then the output is expected to be two line features each containing two vertices, and each a length of 0.8. For area features, the Approximate Length determines the approximate height and width of chopped areas. If vertex spacing along the line is greater than the Approximate Length, larger areas will result. By default, Add Interior Points (Areas Only) is set to Yes, meaning that new vertices may be introduced to the interior of areas.
Add Interior Vertices (Areas Only)	Yes: New vertices will be introduced while chopping up an input area feature whenever needed. These vertices are guaranteed to fall inside the input area. No: No new vertices will be introduced. This means if an input area cannot be chopped up without new vertices within the confines of Approximate Length, then it will be output unmodified. It is also possible that many of the pieces produced by chopping will be larger than the Approximate Length, since no smaller pieces can be generated without introducing interior vertices.
Aggregate Handling	Select whether to deaggregate and process aggregate geometries, or reject them.

Advanced

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

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.

How to Set Parameter Values

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.

Content Types

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.

Table Tools

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 Community

The FME Community is the place for demos, how-tos, articles, FAQs, and more. Get answers to your questions, learn from other users, and suggest, vote, and comment on new features.

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