site Each site in the diagram is an array [x, y] with two additional properties: index - the site’s index, corresponding to the associated input point. data - the input data corresponding to this site.

simulation.velocityDecay([decay]) If decay is specified, sets the velocity decay factor to the specified number in the range [0,1] and returns this simulation. If decay is not specified, returns the current velocity decay factor, which defaults to 0.4. The decay factor is akin to atmospheric friction; after the application of any forces during a tick, each node’s velocity is multiplied by 1 - decay. As with lowering the alpha decay rate, less velocity decay may converge on a better solution,

simulation.tick() Increments the current alpha by (alphaTarget - alpha) × alphaDecay; then invokes each registered force, passing the new alpha; then decrements each node’s velocity by velocity × velocityDecay; lastly increments each node’s position by velocity. This method does not dispatch events; events are only dispatched by the internal timer when the simulation is started automatically upon creation or by calling simulation.restart. The natural number of ticks when the simulation is st

simulation.stop() Stops the simulation’s internal timer, if it is running, and returns the simulation. If the timer is already stopped, this method does nothing. This method is useful for running the simulation manually; see simulation.tick.

simulation.restart() Restarts the simulation’s internal timer and returns the simulation. In conjunction with simulation.alphaTarget or simulation.alpha, this method can be used to “reheat” the simulation during interaction, such as when dragging a node, or to resume the simulation after temporarily pausing it with simulation.stop.

simulation.on(typenames, [listener]) If listener is specified, sets the event listener for the specified typenames and returns this simulation. If an event listener was already registered for the same type and name, the existing listener is removed before the new listener is added. If listener is null, removes the current event listeners for the specified typenames, if any. If listener is not specified, returns the first currently-assigned listener matching the specified typenames, if any. W

simulation.nodes([nodes]) If nodes is specified, sets the simulation’s nodes to the specified array of objects, initializing their positions and velocities if necessary, and then re-initializes any bound forces; returns the simulation. If nodes is not specified, returns the simulation’s array of nodes as specified to the constructor. Each node must be an object. The following properties are assigned by the simulation: index - the node’s zero-based index into nodes x - the node’s current x

simulation.force(name[, force]) If force is specified, assigns the force for the specified name and returns this simulation. If force is not specified, returns the force with the specified name, or undefined if there is no such force. (By default, new simulations have no forces.) For example, to create a new simulation to layout a graph, you might say: var simulation = d3.forceSimulation(nodes) .force("charge", d3.forceManyBody()) .force("link", d3.forceLink(links)) .force("cente

simulation.find(x, y[, radius]) Returns the node closest to the position ⟨x,y⟩ with the given search radius. If radius is not specified, it defaults to infinity. If there is no node within the search area, returns undefined.

simulation.alphaTarget([target]) If target is specified, sets the current target alpha to the specified number in the range [0,1] and returns this simulation. If target is not specified, returns the current target alpha value, which defaults to 0.