pygplates.PropertyValue

class pygplates.PropertyValue

Bases: Boost.Python.instance

The base class inherited by all derived property value classes. Property values are equality (==, !=) comparable (but not hashable - cannot be used as a key in a dict). Two property values will only compare equal if they have the same derived property value type (and the same internal values). For example, a GpmlPlateId property value instance and a XsInteger property value instance will always compare as False.

The list of derived property value classes includes:

The following subset of derived property value classes are topological geometries:

The following subset of derived property value classes are time-dependent wrappers:

You can use get_value() to extract a value at a specific time from a time-dependent wrapper.

A property value can be deep copied using clone().

__init__()

Raises an exception This class cannot be instantiated from Python

Methods

__init__

Raises an exception This class cannot be instantiated from Python

accept_visitor(visitor)

Accept a property value visitor so that it can visit this property value.

clone()

Create a duplicate of this property value (derived) instance, including a recursive copy of any nested property values that this instance might contain.

get_geometry()

Extracts the geometry if this property value contains a geometry.

get_value([time=0])

Extracts the value, of this possibly time-dependent property value, at the reconstruction time.
accept_visitor(visitor)

Accept a property value visitor so that it can visit this property value. As part of the visitor pattern, this enables the visitor instance to discover the derived class type of this property. Note that there is no common interface shared by all property value types, hence the visitor pattern provides one way to find out which type of property value is being visited.

Parameters

visitor (PropertyValueVisitor) – the visitor instance visiting this property value

clone()

Create a duplicate of this property value (derived) instance, including a recursive copy of any nested property values that this instance might contain.

Return type

PropertyValue

get_geometry()

Extracts the geometry if this property value contains a geometry.

Return type

GeometryOnSphere or None

This function searches for a geometry in the following standard geometry property value types:

If this property value does not contain a geometry then None is returned.

Time-dependent geometry properties are not yet supported, so the only time-dependent property value wrapper currently supported by this function is GpmlConstantValue.

To extract geometry from a specific feature property:

property_value = feature.get_value(pygplates.PropertyName.gpml_pole_position)
if property_value:
    geometry = property_value.get_geometry()

…however Feature.get_geometry() provides an easier way to extract geometry from a feature with:

geometry = feature.get_geometry(pygplates.PropertyName.gpml_pole_position)

To extract all geometries from a feature (regardless of which properties they came from):

all_geometries = []
for property in feature:
    property_value = property.get_value()
    if property_value:
        geometry = property_value.get_geometry()
        if geometry:
            all_geometries.append(geometry)

…however again Feature.get_geometry() does this more easily with:

all_geometries = feature.get_geometry(lambda property: True, pygplates.PropertyReturn.all)
get_value([time=0])

Extracts the value, of this possibly time-dependent property value, at the reconstruction time.

Parameters

time (float or GeoTimeInstant) – the time to extract value (defaults to present day)

Return type

PropertyValue or None

If this property value is a time-dependent property (GpmlConstantValue, GpmlIrregularSampling or GpmlPiecewiseAggregation) then a nested property value is extracted at the reconstruction time and returned. Otherwise this property value instance is simply returned as is (since it’s not a time-dependent property value).

Returns None if this property value is a time-dependent property (GpmlConstantValue, GpmlIrregularSampling or GpmlPiecewiseAggregation) and time is outside its time range (of time samples or time windows).

Note that if this property value is a GpmlIrregularSampling instance then the extracted property value is interpolated (at reconstruction time) if property value can be interpolated (currently only GpmlFiniteRotation and XsDouble), otherwise None is returned.

The following example demonstrates extracting an interpolated finite rotation from a total reconstruction pole at time 20Ma:

gpml_finite_rotation_20Ma = total_reconstruction_pole.get_value(20)
if gpml_finite_rotation_20Ma:
  print 'Interpolated finite rotation at 20Ma: %s' % gpml_finite_rotation_20Ma.get_finite_rotation()