确定一组候选特征的密度。
密度是测量候选人values per unit area. It is calculated as a numeric value; the greater the value, the more dense are the候选人特征。
密度方程是总候选人/感兴趣的区域。
Total Candidatesis defined by either:
- 总数候选人特征
- The sum LENGTH of候选人特征
- The sum区域of候选人特征
感兴趣的领域由进入的第一多边形功能的大小定义区域input port.
Caution
It’s VERY important to note that ALL候选人特征count towards the density calculation, even if they fall outside the区域feature.
换句话说，这种变形金机不测试候选对象是否在内部区域feature. If you wish to use only候选人特征that lie within, or overlap, the区域功能，您应该使用SpatialFilter或SpatialRelator变压器预处理数据。
Input Ports
区域
涵盖感兴趣区域的单个参考功能。
候选人
一系列候选人特征。
Output Ports
区域
原本的区域特性添加了密度属性(s)。其value will be the sum of the corresponding候选人特征（它们的数字，长度或区域）除以此功能本身的区域。
候选人
原本的候选人特征和the Density Attribute added. Each候选人in a group will receive the same density value: the sum of the候选人该组的功能除以第一个相应的区域区域feature.
参数
Group Processing
Group By
如果未指定此参数，则ALL候选人特征form a single group, and are processed against a single区域feature. This is the default behavior.
When an attribute is specified for this parameter, then groups are formed where they have matching attribute values. This allows you to process multiple groups of候选人特征against multiple区域特征。
Group By Mode
结束过程（阻塞）：这是默认行为。只有在存在所有输入时，处理将在此变换器中发生。
组更改时的过程（高级）：此变压器将按顺序处理输入组。通过输入流上参数的Group的值的更改将触发当前累积组的处理。这可以提高整体速度（特别是具有多个等大小的组），但如果输入组未真正有序，则可能导致不期望的行为。
Considerations for UsingGroup By
There are two typical reasons for using组更改时的过程（高级）。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 aSQL ORDER BYstatement) 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).
根据数据流的数量，排序变得更加困难。由于所有匹配的功能，多个数据流可能几乎不可能排序到正确的顺序中Group By需要在属于下一个组的任何功能（任何特征类型或数据集）之前到达。在这种情况下，使用Group By和结束过程（阻塞）may be the equivalent and simpler approach.
Note: ">笔记：Multiple feature types and features from multiple datasets will not generally naturally occur in the correct order.
与许多情况一样，使用您的数据测试工作区中的不同方法是识别性能增益的唯一明确方式。
一般的
Calculate Density By
This parameter determines how the total candidates value is calculated. Its possible values are:
- Number of Features
- Line Length
- 区域
通常，此参数与此参数之间的关系候选人几何如下：
| 候选人Geometry | Calculate Density By |
|---|---|
| Points | Number of Features |
| 线 | Line Length |
| 多边形（面积） | 区域 |
When the候选人geometry does not match what is required – for example, point features when Calculate Density By equals Area – then the features are ignored (but still output).
Density Attribute
This parameter defines the attribute that is to receive the calculated density value. The default is_密度。
Usage Notes
- 几何类型的候选人特征may be points, lines, or polygons. However,区域功能必须是多边形。
- 如果过剩区域提供功能 - 即，有多个区域特定组的功能 - 然后将它们排除在密度的计算之外候选人s。However, they will still receive their own density calculation. In other words, each区域receives the density of候选人特点是他们自己的尺寸;但候选人特征only receive their density in relation to the size of the first区域feature.
- If you need to find the density of候选人针对许多多边形功能的总面积的功能，使用聚合器聚合多边形并将结果汇总输入到区域该变压器的港口。
Example
此变压器有许多可能的用途，包括：
疾病密度（每公里的公告数2）
交通网络密度（道路长度每公里2）
土地利用密度（工业区划每公里数量）2）
In this example, the density of cycle route network is calculated for a particular zipcode (postal code).
邮政编码领域：195355642.75英尺2
Total length of cycle route: 83017.28 ft
密度：0.000425
In this example, the cycle routes spatially overlap with the zipcode boundaries, and are clipped to match, but the DensityCalculator does not necessarily need this to be so.
如果有多个Zipcode功能要处理，则使用Zipcode属性作为属性到组的Zipcode属性，可以在DIFESScalculator中使用组。结果将是每个邮政编码的循环路由密度的计数。
编辑变换器参数
使用一组菜单选项,变压器参数s 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, seeTransformer Parameter Menu Options。
Defining Values
有几种方法可以在变压器中定义使用的值。最简单的是简单地输入值或字符串，其可以包括各种类型的函数，例如属性引用，数学和字符串函数和工作区参数。有许多工具和快捷方式可以帮助构造值的值，通常可以从与值字段相邻的下拉上下文菜单中提供。
How to Set Parameter Values
使用文本编辑器
文本编辑器提供了一种方便的方法来构建来自各种数据源的文本字符串（包括正则表达式），例如属性，参数和常量，其中结果直接在参数内使用。
使用算术编辑器
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.
条件值
根据通过或失败的一个或多个测试条件设置值。
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>）不应用作文字字符串值。
内容类型
| 这些功能操纵和格式化字符串。 | |
特殊的角色 |
A set of control characters is available in the Text Editor. |
| Math functions are available in both editors. | |
| 日期/时间函数 | Date and time functions are available in the Text Editor. |
| These operators are available in the Arithmetic Editor. | |
| 这些主要是特定于特征的值。 | |
| 可以使用FME和工作区的参数。 | |
| 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.
表工具
Row Reordering
|
Enabled once you have clicked on a row item. Choices include:
|
剪裁，复制和粘贴
|
Enabled once you have clicked on a row item. Choices include:
切割，复制和粘贴可以在变压器或变压器之间使用。 |
Filter
|
开始键入字符串，矩阵仅显示匹配这些字符的行。搜索所有列。这仅影响变换器内的属性的显示 - 它不会更改输出哪个属性。 |
Import
|
Import populates the table with a set of new attributes read from a dataset. Specific application varies between transformers. |
Reset/Refresh
|
通常将表重置为其初始状态，并且可以提供其他选项以删除无效条目。行为在变压器之间变化。 |
笔记：并非所有变压器都提供所有工具。
Related Transformers
FME社亚搏国际在线官网区
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.
Search for samples and information about this transformer on theFME社亚搏国际在线官网区。