| simulate {particles} | R Documentation |
Start a simulation based on a graph
Description
This function initiates a simulation based on the provided graph and
parameters. Any graph structure with a tidygraph::as_tbl_graph() method
is supported as input. This function does not start the simulation but merely
sets it up.
Usage
simulate(
graph,
alpha = 1,
alpha_min = 0.001,
alpha_decay = 1 - alpha_min^(1/300),
alpha_target = 0,
velocity_decay = 0.4,
setup = phyllotactic_genesis(),
...
)
is.simulation(x)
record(simulation, ...)
clear_history(simulation)
get_history(simulation, age = -1)
history_length(simulation)
reheat(simulation, alpha)
particles(simulation)
position(simulation)
velocity(simulation)
evolutions(simulation)
Arguments
graph |
A graph in a format supported by tidygraph |
alpha |
The starting alpha value. See Details. |
alpha_min |
The minimum alpha value after which the simulation is terminated. See Details. |
alpha_decay |
The speed at which the alpha value decreases. See Details. |
alpha_target |
The alpha value that alpha drifts towards. See Details. |
velocity_decay |
The dampening factor of the system. See Details. |
setup |
A function that takes the particle graph and returns a start
position and velocity to each particle. |
... |
Additional parameters for the simulation (currently ignored) |
x, simulation |
A simulation object |
age |
The version to retrieve. Positive numbers count from the
beginning, while negative numbers counts backwards from current version.
Defaults to |
Details
A simulation in the context of the particles package is a series of
equidistant steps where the velocity and position of each particle is
updated. A few global rules applies to this cycle irrespectively of the
forces added to the simulation. Once a simulation is initiated an alpha
value is defined (defaults to 1). At each step this alpha value is
decreased according to its distance to the alpha_target (defaults to 0)
and alpha_decay (defaults to ~0.023). Once the alpha value gets below
alpha_min (defaults to 0.001) the simulation seizes to take additional
steps. The default values is adapted from the d3-force implementation and
corresponds to 300 steps. Conceptually the alpha progression can be seen
as a cooling off of the system as the value decreases quickly in the
beginning and then slowly reach the target value. If it is not intended to
have a system that cools off, simply set the alpha_target value to the same
as alpha. At each step, after the new particle velocities has been
calculated but before they have been applied to the positions, a dampening
factor (velocity_decay) is applied in order to simulate the gradual loss
of momentum. If this is not intended for the simulation, simply set the value
to 0.
Value
A simulation object
Functions
-
record(): Save the current state in the simulation's history -
clear_history(): Clear the current history from the simulation -
get_history(): Retrieve a simulation from the history -
history_length(): Get the number of versions stored in the history of the simulation -
reheat(): set the cooling of the simulation to a new value -
particles(): Extract the particle graph from a simulation -
position(): Extract the position coordinates from a simulation -
velocity(): Extract the velocity verlets from a simulation -
evolutions(): Get the number of generations the simulation has undergone
Examples
graph <- tidygraph::create_notable('folkman')
graph |>
simulate()