pygplates.NetRotation

class pygplates.NetRotation

Bases: instance

Net rotation of regional or global crust.

NetRotations support addition net_rotation = net_rotation1 + net_rotation2 and net_rotation += other_net_rotation.

NetRotations are not equality (==, !=) comparable (will raise TypeError when compared) and are not hashable (cannot be used as a key in a dict). This stems from the fact that two NetRotations can have equivalent finite rotations but can cover different areas.

A NetRotation can also be pickled.

Added in version 0.43.

__init__(): Creates a zero net rotation.

Methods

`__init__`()	Creates a zero net rotation.
`convert_finite_rotation_to_rotation_rate_vector`(...)	[staticmethod] Convert a `finite rotation` over a time interval to a rotation rate vector (with magnitude in radians per Myr).
`convert_rotation_rate_vector_to_finite_rotation`(...)	[staticmethod] Convert a rotation rate vector (with magnitude in radians per Myr) to a `finite rotation` over a time interval.
`create_sample_from_finite_rotation`(point, ...)	[staticmethod] Creates a net rotation contribution from a finite rotation at a point sample.
`create_sample_from_rotation_rate`(point, ...)	[staticmethod] Creates a net rotation contribution from a rotation rate vector at a point sample.
`get_area`()	Return the sample area covered by the `point samples` used to calculate this net rotation, in steradians (square radians).
`get_finite_rotation`()	Return the net rotation as a finite rotation (over a time interval of 1Myr).
`get_rotation_rate_vector`()	Return the net rotation as a rotation rate vector with a magnitude of radians per Myr.

static convert_finite_rotation_to_rotation_rate_vector(finite_rotation[, time_interval=1.0])

[staticmethod] Convert a finite rotation over a time interval to a rotation rate vector (with magnitude in radians per Myr).

Parameters:

finite_rotation (FiniteRotation) – The finite rotation over the specified time interval.
time_interval (float) – The time interval of the specified finite rotation (defaults to 1Myr).

Return type:

Vector3D

To convert a finite rotation over 10Myr to a rotation rate vector (in radians per Myr):

net_rotation_rate_vector = pygplates.NetRotation.convert_finite_rotation_to_rotation_rate_vector(net_finite_rotation_over_10myr, 10)

static convert_rotation_rate_vector_to_finite_rotation(rotation_rate_vector[, time_interval=1.0])

[staticmethod] Convert a rotation rate vector (with magnitude in radians per Myr) to a finite rotation over a time interval.

Parameters:

rotation_rate_vector (Vector3D) – The rotation rate vector (with magnitude in radians per Myr).
time_interval (float) – The time interval of the returned finite rotation (defaults to 1Myr).

Return type:

FiniteRotation

To convert a rotation rate vector (in radians per Myr) to a finite rotation over 10Myr (ie, having the same pole but with an angle multiplied by 10):

net_finite_rotation_over_10myr = pygplates.NetRotation.convert_rotation_rate_vector_to_finite_rotation(net_rotation_rate_vector, 10)

static create_sample_from_finite_rotation(point, sample_area, finite_rotation[, time_interval=1.0])

[staticmethod] Creates a net rotation contribution from a finite rotation at a point sample.

Parameters:

point (PointOnSphere or LatLonPoint or tuple (latitude,longitude), in degrees, or tuple (x,y,z)) – The point that contributes to net rotation.
sample_area (float) – The surface area around the point in steradians (square radians).
finite_rotation (FiniteRotation) – The finite rotation over the specified time interval.
time_interval (float) – The time interval of the specified finite rotation (defaults to 1Myr).

Return type:

NetRotation

In this contrived example we calculate the net rotation of a single plate. This is just for demonstration purposes in case you wanted to do your own intersections of point samples with plates (otherwise it’s easier to just use NetRotationSnapshot which does all this for you).

# Let's assume you have a plate and know its finite rotation (over 1Myr), and you have a list of
# (lat, lon) tuples which are those points on a uniform lat-lon grid that are inside the plate.
plate_finite_rotation = ...
lat_lon_tuples_inside_plate = [...]
lat_lon_grid_spacing_in_degrees = ...
lat_lon_grid_spacing_in_radians = math.radians(lat_lon_grid_spacing_in_degrees)

# We'll accumulate net rotation over the point samples inside the plate.
plate_net_rotation_accumulator = pygplates.NetRotation()  # start with zero net rotation

for lat, lon in lat_lon_tuples_inside_plate:
    # The cosine is because points near the North/South poles are closer together
    # (latitude parallel small circle radius).
    sample_area_radians = math.cos(math.radians(lat)) * lat_lon_grid_spacing_in_radians * lat_lon_grid_spacing_in_radians
    plate_net_rotation_accumulator += pygplates.NetRotation.create_sample_from_finite_rotation(
            pygplates.LatLonPoint(lat, lon), sample_area_radians, plate_finite_rotation)

plate_net_rotation = plate_net_rotation_accumulator.get_finite_rotation()

static create_sample_from_rotation_rate(point, sample_area, rotation_rate_vector)

[staticmethod] Creates a net rotation contribution from a rotation rate vector at a point sample.

Parameters:

point (PointOnSphere or LatLonPoint or tuple (latitude,longitude), in degrees, or tuple (x,y,z)) – The point that contributes to net rotation.
sample_area (float) – The surface area around the point in steradians (square radians).
rotation_rate_vector (Vector3D) – The rotation rate vector (with magnitude in radians per Myr).

Return type:

NetRotation