# space_ops¶

Utility functions for two- and three-dimensional vectors.

Functions

R3_to_complex(point)[source]
Parameters

point (Sequence[float]) –

Return type

numpy.ndarray

angle_axis_from_quaternion(quaternion)[source]

Gets angle and axis from a quaternion.

Parameters

quaternion (Sequence[float]) – The quaternion from which we get the angle and axis.

Returns

Gives the angle and axis

Return type

Sequence[float]

angle_between_vectors(v1, v2)[source]

Returns the angle between two vectors. This angle will always be between 0 and pi

Parameters
• v1 (numpy.ndarray) – The first vector.

• v2 (numpy.ndarray) – The second vector.

Returns

The angle between the vectors.

Return type

np.ndarray

angle_of_vector(vector)[source]

Returns polar coordinate theta when vector is projected on xy plane.

Parameters

vector (Sequence[float]) – The vector to find the angle for.

Returns

The angle of the vector projected.

Return type

float

cartesian_to_spherical(vec)[source]

Returns an array of numbers corresponding to each polar coordinate value (distance, phi, theta).

Parameters

vec (Sequence[float]) – A numpy array `[x, y, z]`.

Return type

numpy.ndarray

center_of_mass(points)[source]

Gets the center of mass of the points in space.

Parameters

points (Sequence[float]) – The points to find the center of mass from.

Returns

The center of mass of the points.

Return type

np.ndarray

compass_directions(n=4, start_vect=array([1., 0., 0.]))[source]

Finds the cardinal directions using tau.

Parameters
• n (int) – The amount to be rotated, by default 4

• start_vect (numpy.ndarray) – The direction for the angle to start with, by default RIGHT

Returns

The angle which has been rotated.

Return type

np.ndarray

complex_func_to_R3_func(complex_func)[source]
complex_to_R3(complex_num)[source]
Parameters

complex_num (complex) –

Return type

numpy.ndarray

cross2d(a, b)[source]
earclip_triangulation(verts, ring_ends)[source]

Returns a list of indices giving a triangulation of a polygon, potentially with holes.

Parameters
• verts (numpy.ndarray) – verts is a numpy array of points.

• ring_ends (list) – ring_ends is a list of indices indicating where

• are. (the ends of new paths) –

Returns

A list of indices giving a triangulation of a polygon.

Return type

list

find_intersection(p0, v0, p1, v1, threshold=1e-05)[source]

Return the intersection of a line passing through p0 in direction v0 with one passing through p1 in direction v1. (Or array of intersections from arrays of such points/directions). For 3d values, it returns the point on the ray p0 + v0 * t closest to the ray p1 + v1 * t

Return type

numpy.ndarray

get_unit_normal(v1, v2, tol=1e-06)[source]

Gets the unit normal of the vectors.

Parameters
• v1 (numpy.ndarray) – The first vector.

• v2 (numpy.ndarray) – The second vector

• tol (float) – [description], by default 1e-6

Returns

The normal of the two vectors.

Return type

np.ndarray

get_winding_number(points)[source]
Parameters

points (Sequence[float]) –

Return type

float

line_intersection(line1, line2)[source]

Returns intersection point of two lines, each defined with a pair of vectors determining the end points.

Parameters
• line1 (Sequence[float]) – The first line.

• line2 (Sequence[float]) – The second line.

Returns

The intersection points of the two lines which are intersecting.

Return type

np.ndarray

Raises

ValueError – Error is produced if the two lines don’t intersect with each other

midpoint(point1, point2)[source]

Gets the midpoint of two points.

Parameters
• point1 (Sequence[float]) – The first point.

• point2 (Sequence[float]) – The second point.

Returns

The midpoint of the points

Return type

Union[float, np.ndarray]

norm_squared(v)[source]
Parameters

v (float) –

Return type

float

normalize(vect, fall_back=None)[source]
Parameters

vect (Union[numpy.ndarray, Tuple[float]]) –

Return type

numpy.ndarray

normalize_along_axis(array, axis)[source]

Normalizes an array with the provided axis.

Parameters
• array (numpy.ndarray) – The array which has to be normalized.

• axis (numpy.ndarray) – The axis to be normalized to.

Returns

Array which has been normalized according to the axis.

Return type

np.ndarray

perpendicular_bisector(line, norm_vector=array([0., 0., 1.]))[source]

Returns a list of two points that correspond to the ends of the perpendicular bisector of the two points given.

Parameters
• line (Sequence[numpy.ndarray]) – a list of two numpy array points (corresponding to the ends of a line).

• norm_vector – the vector perpendicular to both the line given and the perpendicular bisector.

Returns

A list of two numpy array points that correspond to the ends of the perpendicular bisector

Return type

list

project_along_vector(point, vector)[source]

Projects a vector along a point.

Parameters
• point (float) – The point to be project from.

• vector (numpy.ndarray) – The vector which has to projected.

Returns

A dot product of the point and vector.

Return type

np.ndarray

quaternion_conjugate(quaternion)[source]

Used for finding the conjugate of the quaternion

Parameters

quaternion (Sequence[float]) – The quaternion for which you want to find the conjugate for.

Returns

The conjugate of the quaternion.

Return type

np.ndarray

quaternion_from_angle_axis(angle, axis, axis_normalized=False)[source]

Parameters
• angle (float) – The angle for the quaternion.

• axis (numpy.ndarray) – The axis for the quaternion

• axis_normalized (bool, optional) – Checks whether the axis is normalized, by default False

Returns

Gives back a quaternion from the angle and axis

Return type

List[float]

quaternion_mult(*quats)[source]

Returns

Returns a list of product of two quaternions.

Return type

Union[np.ndarray, List[Union[float, np.ndarray]]]

Parameters

quats (Sequence[float]) –

Generates regularly spaced vertices around a circle centered at the origin.

Parameters
• n (int) – The number of vertices

• radius (float) – The radius of the circle that the vertices are placed on.

• start_angle (Optional[float]) –

The angle the vertices start at.

If unspecified, for even `n` values, `0` will be used. For odd `n` values, 90 degrees is used.

Returns

• vertices (`numpy.ndarray`) – The regularly spaced vertices.

• start_angle (`float`) – The angle the vertices start at.

Return type

Tuple[numpy.ndarray, float]

rotate_vector(vector, angle, axis=array([0., 0., 1.]))[source]

Function for rotating a vector.

Parameters
• vector (numpy.ndarray) – The vector to be rotated.

• angle (int) – The angle to be rotated by.

• axis (numpy.ndarray) – The axis to be rotated, by default OUT

Returns

The rotated vector with provided angle and axis.

Return type

np.ndarray

Raises

ValueError – If vector is not of dimension 2 or 3.

Returns a rotation matrix for a given angle.

Parameters

angle (float) – Angle for the rotation matrix.

Returns

Gives back the rotated matrix.

Return type

List[float]

rotation_matrix(angle, axis, homogeneous=False)[source]

Rotation in R^3 about a specified axis of rotation.

Parameters
• angle (float) –

• axis (numpy.ndarray) –

• homogeneous (bool) –

Return type

numpy.ndarray

rotation_matrix_from_quaternion(quat)[source]
Parameters

quat (numpy.ndarray) –

Return type

numpy.ndarray

rotation_matrix_transpose(angle, axis)[source]
Parameters
• angle (float) –

• axis (numpy.ndarray) –

Return type

numpy.ndarray

rotation_matrix_transpose_from_quaternion(quat)[source]

Parameters

quat (numpy.ndarray) – The quaternion which is to be converted.

Returns

Gives back the Rotation matrix representation, returned as a 3-by-3 matrix or 3-by-3-by-N multidimensional array.

Return type

List[np.ndarray]

shoelace(x_y)[source]

2D implementation of the shoelace formula.

Returns

Returns signed area.

Return type

`float`

Parameters

x_y (numpy.ndarray) –

shoelace_direction(x_y)[source]

Uses the area determined by the shoelace method to determine whether the input set of points is directed clockwise or counterclockwise.

Returns

Either `"CW"` or `"CCW"`.

Return type

`str`

Parameters

x_y (numpy.ndarray) –

spherical_to_cartesian(spherical)[source]

Returns a numpy array `[x, y, z]` based on the spherical coordinates given.

Parameters

spherical (Sequence[float]) –

A list of three floats that correspond to the following:

r - The distance between the point and the origin.

theta - The azimuthal angle of the point to the positive x-axis.

phi - The vertical angle of the point to the positive z-axis.

Return type

numpy.ndarray

thick_diagonal(dim, thickness=2)[source]
Parameters

dim (int) –

Return type

numpy.ndarray

z_to_vector(vector)[source]

Returns some matrix in SO(3) which takes the z-axis to the (normalized) vector provided as an argument

Parameters

vector (numpy.ndarray) –

Return type

numpy.ndarray