Package org.apache.sis.feature

Defines the structure and content of views of real-world phenomenon.

See: Description

Class Summary

Class	Description
AbstractAssociation	An instance of an feature association role containing the associated feature.
AbstractAttribute<V>	An instance of an attribute type containing the value of an attribute in a feature.
AbstractFeature	An instance of a feature type containing values for a real-world phenomena.
AbstractIdentifiedType	Identification and description information inherited by property types and feature types.
AbstractOperation	Describes the behaviour of a feature type as a function or a method.
DefaultAssociationRole	Indicates the role played by the association between two features.
DefaultAttributeType<V>	Definition of an attribute in a feature type.
DefaultFeatureType	Abstraction of a real-world phenomena.
FeatureFormat	Formats features or feature types in a tabular format.
FeatureOperations	A set of pre-defined operations expecting a Feature as input and producing an Attribute as output.
Features	Static methods working on features or attributes.

Enum Summary

Enum	Description
FeatureFormat.Column	Identifies the columns to include in the table formatted by Feature­Format.

Package org.apache.sis.feature Description

Defines the structure and content of views of real-world phenomenon. The phenomenon to represent (or a fundamental unit of information) is called a feature. The term “feature” may be used in different contexts:

• Feature types
  Define the structure of real-world representations. A feature type lists the attributes, operations or associations to other features (collectively called “properties” or “characteristics”) that a feature can have.
  Analogy: a Feature­Type in a Spatial Information System is equivalent to a Class in the Java language. By extension, Attribute­Type and Operation are equivalent to Field and Method respectively.
• Feature instances (often called only Features)
  Hold the content (or values) that describe one specific real-world object.
  Example: the “Eiffel tower” is a feature instance belonging to the “Tower” feature type.
• Simple features
  Are instances of a feature type with no association to other features, and where all attributes are constrained to the [1 … 1] cardinality. Such simple features are very common.

In addition, a feature type can inherit the properties of one or more other feature types. Properties defined in the sub-type can override properties of the same name defined in the super-types, provided that values of the sub-type property are assignable to the super-type property.

Naming

Each feature type has a name, which should be unique. Those names are the main criterion used for checking if a feature type is assignable from another type. Names can be scoped for avoiding name collision.

Class hierarchy

The class hierarchy for feature types is derived from ISO 19109 specification. The class hierarchy for feature instances is closely related:

Feature class hierarchy

Types	Instances
Identified type ├─ Feature type └─ Property type ├─ Attribute type ├─ Feature association role └─ Operation	Object ├─ Feature (sparse or dense) └─ Property ├─ Attribute (singleton or multi-valued) └─ Feature association (singleton or multi-valued)

Instantiation

Classes defined in this package are rarely instantiated directly (by a new statement). Instead those classes are instantiated indirectly by invoking a method on a parent container, or by using a builder. The starting point is Feature­Type, which may be created by a Feature­Type­Builder or may be provided by a Data­Store reading a data file. Once a Feature­Type has been obtained, Features can be instantiated by calls to the Feature­Type.new­Instance() method. Once a Feature instance has been obtained, Attributes can be instantiated indirectly by calls to the Feature.set­Property­Value(…) method.

Since:

0.5

Defined in the sis-feature module