2DGridAccumulator

Categories

Geometries

Replaces the input features with a grid of two-dimensional point or polygon features having the spacing specified covering (at least) the bounding box area of all the features which enter the transformer.

Configuration

Input Ports

This transformer accepts any feature.

Output Ports

The grid of point or polygon features covering the bounding box area of the input features.

Features with non-numeric attributes for Column Width and Row Height or Number of Horizontal Tiles and Number of Vertical Tiles are output through this port. However, once a feature with numeric values in these attributes is received, all following features will use these same attribute values and will not be rejected.

Rejected features will have an fme_rejection_code attribute with one of the following values: INVALID_GEOMETRY_TYPE, INVALID_PARAMETER_SURFACE_NORMAL_DEVIATION, INVALID_PARAMETER_THICKNESS.

Parameters

Group By

The input features may be partitioned into groups based on attribute values and one bounding box feature is output for each group. If you do not specify any Group By attributes, all input features will be processed together and a single bounding box will be output.

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.

Grid Type

Specifies how the grid size will be defined. Cell Size will enable the Column Width and Row Height parameters, while Number of Cells will enable the Number of Horizontal/Vertical Tiles parameters.

Starting Corner

Chooses a starting corner for the purposes of numbering rows and columns. Also, when Grid Type is Cell Size, the last row and/or the last column may extend beyond the bounds of the input features; here the “last” row or column is the one opposite the Starting Corner.

Type of Grid to Create

Choose point or polygon features.

Choosing Polygons will generate rectangular boxes with the specified column width and row height.

If Points (Corners) is selected, the corners of all the rectangles in the grid will be output. Points (Centers) will generate the middle point of each rectangle.

Note that there will be more features output for Points (Corners) than for either of Polygons and Points (Centers), since there will be one additional row and one additional column.

Cell Size

 

When Grid Type is Cell Size:

Column Width / Row Height (ground units)

The Column Width and Row Height parameters specify in ground units the distance between output points in the grid or the width and height of the output polygons.

Note: If you use attribute values as the Column Width and/or Row Height, only the attributes of the first encountered feature of each group are used. These attributes will be ignored for any following features from the same group.

Seed Coordinate X/Y

These optional parameters specify a "seed point" from which cells will be generated. Note that it is permissible to specify a value for only one of these parameters—not necessarily both.

Number of Cells

 

When Grid Type is Number of Cells:

Number of Horizontal / Vertical Tiles

Specify how to tile the input data (for example, 5 horizontal tiles and 5 vertical tiles).

Note: If you use attribute values as the Number of Horizontal Tiles and/or Number of Vertical Tiles, only the attributes of the first encountered feature of each group are used. These attributes will be ignored for any following features from the same group.

Column

If Column Attribute or Row Attribute are specified, attributes will be added to each output tile that identify the position of that tile in the input raster. These indices are zero-based, beginning at the specified Starting Corner.

Row

If Column Attribute or Row Attribute are specified, attributes will be added to each output tile that identify the position of that tile in the input raster. These indices are zero-based, beginning at the specified Starting Corner.

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.

Reference

Processing Behavior

Feature-Based

Feature Holding

No
Dependencies None
Aliases 2DGridReplacer
History  

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Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.