CoordinateRounder
Rounds off the coordinates of the feature to the specified number of decimal places. Any consecutive points that become duplicates as a result of the rounding are thinned by removing the redundant points.
For arcs, only the start and end points are rounded, as these are the only coordinates which lie on the path of the arc. The center point is not rounded, nor are any other of the arc's parameters.
This transformer may be used to remove superfluous decimal points in the coordinates when they are destined for an ASCII output file.
CoordinateRounder may not always behave as some might expect due to limitations in floatingpoint processing. Some numbers like 1.1 cannot be stored precisely in binary and so end up as 1.1000000000000001, regardless of rounding. Rounding to 3 decimal places, results in 1.1000000000000001. Similarly, a value of 3.3333 is stored as 3.3332999999999999, and when rounded to 2 decimal places ends up as 3.3300000000000002.
Note that you won't always see the same effect in the AttributeRounder since some attributes may treat numeric values as strings until the are evaluated in a formula or written out. So, the AttributeRounder may appear to round to 3.33. Still, when the value is actually used, the processor will end up using a value of 3.3300000000000002. On the other hand, coordinates in FME are typically logged with full floatingpoint precision, including any floatingpoint processing precision error. Note that many formats have a way of controlling decimal precision based on data types or precision as set on the writer.
The precision values control the number of decimal places that the coordinates are rounded to. A value of 0 causes the coordinates to be rounded to the nearest integer. A value of 1 causes rounding to the nearest tenth of a unit. Negative values are allowed. A value of 1 causes rounding to the nearest 10.
Each parameter may either be entered as a number, or can be taken from the value of a feature attribute by selecting the attribute name from the pulldown list.
Example
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 dropdown 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.
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.
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.
These functions manipulate and format strings.  
Special Characters 
A set of control characters is available in the Text Editor. 
Math functions are available in both editors.  
Date/Time Functions  Date and time functions are available in the Text Editor. 
These operators are available in the Arithmetic Editor.  
These return primarily featurespecific values.  
FME and workspacespecific parameters may be used.  
Creating and Modifying User Parameters  Create your own editable parameters. 
Dialog Options  Tables
Transformers with tablestyle parameters have additional tools for populating and manipulating values.
Row Reordering

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

Cut, Copy, and Paste

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