Motions

This module contains functionality related to motions (continuous flexes).

class pyrigi.motion.Motion(graph)

Bases: object

An abstract class representing a continuous flex of a framework.

Parameters:

graph (Graph)

class pyrigi.motion.ParametricMotion(graph, motion, interval)

Bases: Motion

Class representing a parametric motion.

Definitions

Continuous flex (motion)

Parameters:

• graph (Graph)

• motion (dict[Hashable, Sequence[int | float | str]]) – A parametrization of a continuous flex using SymPy expressions, or strings that can be parsed by SymPy.

• interval (tuple) – The interval in which the parameter is considered.

Examples

>>> from pyrigi.motion import ParametricMotion
>>> import sympy as sp
>>> from pyrigi import graphDB as graphs
>>> motion = ParametricMotion(
...     graphs.Cycle(4),
...     {
...         0: ("0", "0"),
...         1: ("1", "0"),
...         2: ("4 * (t**2 - 2) / (t**2 + 4)", "12 * t / (t**2 + 4)"),
...         3: (
...             "(t**4 - 13 * t**2 + 4) / (t**4 + 5 * t**2 + 4)",
...             "6 * (t**3 - 2 * t) / (t**4 + 5 * t**2 + 4)",
...         ),
...     },
...     [-sp.oo, sp.oo],
... )
>>> motion
ParametricMotion of a Graph with vertices [0, 1, 2, 3] and edges [[0, 1], [0, 3], [1, 2], [2, 3]] with motion defined for every vertex:
0: Matrix([[0], [0]])
1: Matrix([[1], [0]])
2: Matrix([[(4*t**2 - 8)/(t**2 + 4)], [12*t/(t**2 + 4)]])
3: Matrix([[(t**4 - 13*t**2 + 4)/(t**4 + 5*t**2 + 4)], [(6*t**3 - 12*t)/(t**4 + 5*t**2 + 4)]])

animate(width=500, height=500, filename=None, sampling=50, show_labels=True, vertex_size=5, duration=8)

Animate the parametric motion.

Parameters:

• width (int) – The width of the window in the svg file.

• height (int) – The height of the window in the svg file.

• filename (str | None) – A name used to store the svg. If None`, the svg is not saved.

• sampling (int) – The number of discrete points or frames used to approximate the motion in the animation. A higher value results in a smoother and more accurate representation of the motion, while a lower value can speed up rendering but may lead to a less precise or jerky animation. This parameter controls the resolution of the animation’s movement by setting the density of sampled data points between keyframes or time steps.

• show_labels (bool) – If True, the vertices will have a number label.

• vertex_size (int) – The size of vertices in the animation.

• duration (int) – The duration of one period of the animation in seconds.

Return type:

None

check_edge_lengths()

Check whether the saved motion preserves edge lengths.

Return type:

bool

realization(value, numeric=False)

Return specific realization for the given value of the parameter.

Parameters:

numeric (bool)

Return type:

dict[slice(Hashable, collections.abc.Sequence[int | float | str], None)]