Module: RGeo::Feature::Geometry

Extended by:
Type
Included in:
Curve, GeometryCollection, Point, Surface
Defined in:
lib/rgeo/feature/geometry.rb

Overview

SFS 1.1 Description

Geometry is the root class of the hierarchy. Geometry is an abstract (non-instantiable) class.

The instantiable subclasses of Geometry defined in this International Standard are restricted to 0, 1 and 2-dimensional geometric objects that exist in 2-dimensional coordinate space (R2).

All instantiable Geometry classes described in this part of ISO 19125 are defined so that valid instances of a Geometry class are topologically closed, i.e. all defined geometries include their boundary.

Notes

Geometry is defined as a module and is provided primarily for the sake of documentation. Implementations need not necessarily include this module itself. Therefore, you should not depend on the result of is_a?(Geometry) to check type. Instead, use the provided check_type class method (or === operator) defined in the Type module.

Some implementations may support higher dimensional objects or coordinate systems, despite the limits of the SFS.

Forms of equivalence

The Geometry model defines three forms of equivalence.

  • Spatial equivalence is the weakest form of equivalence, indicating that the objects represent the same region of space, but may be different representations of that region. For example, POINT(0 0) and a MULTIPOINT(0 0) are spatially equivalent, as are LINESTRING(0 0, 10 10) and GEOMETRYCOLLECTION(POINT(0 0), LINESTRING(0 0, 10 10, 0 0)). As a general rule, objects must have factories that are Factory#eql? in order to be spatially equivalent.

  • Representational equivalence is a stronger form, indicating that the objects have the same representation, but may be different objects. All representationally equivalent objects are spatially equivalent, but not all spatially equivalent objects are representationally equivalent. For example, none of the examples in the spatial equivalence section above are representationally equivalent. However, two separate objects that both represent POINT(1 2) are representationally equivalent as well as spatially equivalent.

  • Objective equivalence is the strongest form, indicating that the references refer to the same object. Of course, all pairs of references with the same objective identity are also both representationally and spatially equivalent.

Different methods test for different types of equivalence:

  • equals? and == test for spatial equivalence.

  • rep_equals? and eql? test for representational equivalence.

  • equal? tests for objective equivalence.

All ruby objects must provide a suitable test for objective equivalence. Normally, this is simply provided by the Ruby Object base class. Geometry implementations should normally also provide tests for representational and spatial equivalence, if possible. The == operator and the eql? method are standard Ruby methods that are often expected to be usable for every object. Therefore, if an implementation cannot provide a suitable test for their equivalence types, they must degrade to use a stronger form of equivalence.

Instance Method Summary collapse

Methods included from Type

add_subtype, check_type, each_immediate_subtype, extended, subtype_of?, supertype, type_name

Instance Method Details

#*(rhs) ⇒ Object

If the given rhs is a geometry object, this operator must behave the same as the intersection method. The behavior for other rhs types is not specified; an implementation may choose to provide additional capabilities as appropriate.


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# File 'lib/rgeo/feature/geometry.rb', line 632

def *(rhs)
  intersection(rhs)
end

#+(rhs) ⇒ Object

If the given rhs is a geometry object, this operator must behave the same as the union method. The behavior for other rhs types is not specified; an implementation may choose to provide additional capabilities as appropriate.


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# File 'lib/rgeo/feature/geometry.rb', line 623

def +(rhs)
  union(rhs)
end

#-(rhs) ⇒ Object

If the given rhs is a geometry object, this operator must behave the same as the difference method. The behavior for other rhs types is not specified; an implementation may choose to provide additional capabilities as appropriate.


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# File 'lib/rgeo/feature/geometry.rb', line 614

def -(rhs)
  difference(rhs)
end

#==(rhs) ⇒ Object

This operator should behave almost the same as the equals? method, with two key differences.

First, the == operator is required to handle rhs values that are not geometry objects (returning false in such cases) in order to fulfill the standard Ruby contract for the == operator, whereas the equals? method may assume that any rhs is a geometry.

Second, the == operator should always be defined. That is, it should never raise Error::UnsupportedOperation. In cases where the underlying implementation cannot provide a spatial equivalence test, the == operator must fall back on representational or objective equivalence.


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# File 'lib/rgeo/feature/geometry.rb', line 597

def ==(rhs)
  if rhs.is_a?(RGeo::Feature::Instance)
    begin
      equals?(rhs)
    rescue Error::UnsupportedOperation
      eql?(rhs)
    end
  else
    false
  end
end

#as_binary ⇒ Object

SFS 1.1 Description

Exports this geometric object to a specific Well-known Binary Representation of Geometry.

Notes

Returns a binary string.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 179

def as_binary
  raise Error::UnsupportedOperation, "Method Geometry#as_binary not defined."
end

#as_text ⇒ Object

SFS 1.1 Description

Exports this geometric object to a specific Well-known Text Representation of Geometry.

Notes

Returns an ASCII string.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 166

def as_text
  raise Error::UnsupportedOperation, "Method Geometry#as_text not defined."
end

#boundary ⇒ Object

SFS 1.1 Description

Returns the closure of the combinatorial boundary of this geometric object. Because the result of this function is a closure, and hence topologically closed, the resulting boundary can be represented using representational Geometry primitives.

Notes

Returns an object that supports the Geometry interface.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 226

def boundary
  raise Error::UnsupportedOperation, "Method Geometry#boundary not defined."
end

#buffer(_distance_) ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents all Points whose distance from this geometric object is less than or equal to distance. Calculations are in the spatial reference system of this geometric object.

Notes

Returns an object that supports the Geometry interface.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 438

def buffer(_distance_)
  raise Error::UnsupportedOperation, "Method Geometry#buffer not defined."
end

#contains?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object “spatially contains” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 359

def contains?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#contains? not defined."
end

#convex_hull ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents the convex hull of this geometric object.

Notes

Returns an object that supports the Geometry interface.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 451

def convex_hull
  raise Error::UnsupportedOperation, "Method Geometry#convex_hull not defined."
end

#crosses?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object “spatially crosses” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 321

def crosses?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#crosses? not defined."
end

#difference(another_geometry) ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents the Point set difference of this geometric object with another_geometry.

Notes

Returns an object that supports the Geometry interface.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of performing operations on objects from different factories is undefined.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 505

def difference(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#difference not defined."
end

#dimension ⇒ Object

SFS 1.1 Description

The inherent dimension of this geometric object, which must be less than or equal to the coordinate dimension. This specification is restricted to geometries in 2-dimensional coordinate space.

Notes

Returns an integer. This value is -1 for an empty geometry, 0 for point geometries, 1 for curves, and 2 for surfaces.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 107

def dimension
  raise Error::UnsupportedOperation, "Method Geometry#dimension not defined."
end

#disjoint?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object is “spatially disjoint” from another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 264

def disjoint?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#disjoint? not defined."
end

#distance(another_geometry) ⇒ Object

SFS 1.1 Description

Returns the shortest distance between any two Points in the two geometric objects as calculated in the spatial reference system of this geometric object.

Notes

Returns a floating-point scalar value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of measuring the distance between objects from different factories is undefined.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 423

def distance(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#distance not defined."
end

#envelope ⇒ Object

SFS 1.1 Description

The minimum bounding box for this Geometry, returned as a Geometry. The polygon is defined by the corner points of the bounding box [(MINX, MINY), (MAXX, MINY), (MAXX, MAXY), (MINX, MAXY), (MINX, MINY)].

Notes

Returns an object that supports the Geometry interface.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 153

def envelope
  raise Error::UnsupportedOperation, "Method Geometry#envelope not defined."
end

#eql?(rhs) ⇒ Boolean

This method should behave almost the same as the rep_equals? method, with two key differences.

First, the eql? method is required to handle rhs values that are not geometry objects (returning false in such cases) in order to fulfill the standard Ruby contract for the method, whereas the rep_equals? method may assume that any rhs is a geometry.

Second, the eql? method should always be defined. That is, it should never raise Error::UnsupportedOperation. In cases where the underlying implementation cannot provide a representational equivalence test, this method must fall back on objective equivalence.

Returns:

  • (Boolean) 

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# File 'lib/rgeo/feature/geometry.rb', line 571

def eql?(rhs)
  if rhs.is_a?(RGeo::Feature::Instance)
    begin
      rep_equals?(rhs)
    rescue Error::UnsupportedOperation
      equal?(rhs)
    end
  else
    false
  end
end

#equals?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object is “spatially equal” to another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 245

def equals?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#equals? not defined."
end

#factory ⇒ Object

Returns a factory for creating features related to this one. This does not necessarily need to be the same factory that created this object, but it should create objects that are “compatible” with this one. (i.e. they should be in the same spatial reference system by default, and it should be possible to perform relational operations on them.)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 92

def factory
  raise Error::UnsupportedOperation, "Method Geometry#factory not defined."
end

#geometry_type ⇒ Object

SFS 1.1 Description

Returns the instantiable subtype of Geometry of which this geometric object is an instantiable member.

Notes

Returns one of the type modules in RGeo::Feature. e.g. a point object would return RGeo::Feature::Point. Note that this is different from the SFS specification, which stipulates that the string name of the type is returned. To obtain the name string, call the type_name method of the returned module.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 124

def geometry_type
  raise Error::UnsupportedOperation, "Method Geometry#geometry_type not defined."
end

#intersection(another_geometry) ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents the Point set intersection of this geometric object with another_geometry.

Notes

Returns an object that supports the Geometry interface.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of performing operations on objects from different factories is undefined.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 469

def intersection(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#intersection not defined."
end

#intersects?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object “spatially intersects” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 283

def intersects?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#intersects? not defined."
end

#is_empty? ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object is the empty Geometry. If true, then this geometric object represents the empty point set for the coordinate space.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 194

def is_empty?
  raise Error::UnsupportedOperation, "Method Geometry#is_empty? not defined."
end

#is_simple? ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object has no anomalous geometric points, such as self intersection or self tangency. The description of each instantiable geometric class will include the specific conditions that cause an instance of that class to be classified as not simple.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 211

def is_simple?
  raise Error::UnsupportedOperation, "Method Geometry#is_simple? not defined."
end

#overlaps?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object “spatially overlaps” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 378

def overlaps?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#overlaps? not defined."
end

#relate?(another_geometry, _intersection_pattern_matrix_) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object is spatially related to another_geometry by testing for intersections between the interior, boundary and exterior of the two geometric objects as specified by the values in the intersection_pattern_matrix.

Notes

The intersection_pattern_matrix is provided as a nine-character string in row-major order, representing the dimensionalities of the different intersections in the DE-9IM. Supported characters include T, F, *, 0, 1, and 2.

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 404

def relate?(another_geometry, _intersection_pattern_matrix_)
  raise Error::UnsupportedOperation, "Method Geometry#relate not defined."
end

#rep_equals?(another_geometry) ⇒ Boolean

Returns true if this geometric object is representationally equivalent to the given object.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 535

def rep_equals?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#rep_equals? not defined."
end

#srid ⇒ Object

SFS 1.1 Description

Returns the Spatial Reference System ID for this geometric object.

Notes

Returns an integer.

This will normally be a foreign key to an index of reference systems stored in either the same or some other datastore.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 139

def srid
  raise Error::UnsupportedOperation, "Method Geometry#srid not defined."
end

#sym_difference(another_geometry) ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents the Point set symmetric difference of this geometric object with another_geometry.

Notes

Returns an object that supports the Geometry interface.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of performing operations on objects from different factories is undefined.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 523

def sym_difference(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#sym_difference not defined."
end

#touches?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object “spatially touches” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 302

def touches?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#touches? not defined."
end

#unary_union ⇒ Object

Unions a collection of Geometry or a single Geometry (which may be a collection) together. By using this special-purpose operation over a collection of geometries it is possible to take advantage of various optimizations to improve performance. Heterogeneous GeometryCollections are fully supported.

This is not a standard SFS method, but when it is available in GEOS, it is a very performant way to union all the geometries in a collection. GEOS version 3.3 or greater is required. If the feature is not available, unary_union returns nil.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 552

def unary_union
  raise Error::UnsupportedOperation, "Method Geometry#unary_union not defined."
end

#union(another_geometry) ⇒ Object

SFS 1.1 Description

Returns a geometric object that represents the Point set union of this geometric object with another_geometry.

Notes

Returns an object that supports the Geometry interface.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of performing operations on objects from different factories is undefined.

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 487

def union(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#union not defined."
end

#within?(another_geometry) ⇒ Boolean

SFS 1.1 Description

Returns true if this geometric object is “spatially within” another_geometry.

Notes

Returns a boolean value. Note that this is different from the SFS specification, which stipulates an integer return value.

Although implementations are free to attempt to handle another_geometry values that do not share the same factory as this geometry, strictly speaking, the result of comparing objects from different factories is undefined.

Returns:

  • (Boolean)

Raises:


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# File 'lib/rgeo/feature/geometry.rb', line 340

def within?(another_geometry)
  raise Error::UnsupportedOperation, "Method Geometry#within? not defined."
end