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digraph_spring_layout(graph, pos=None, fixed=None, k=None, repulsive_exponent=2, adaptive_cooling=True, num_iter=50, tol=1e-06, weight_fn=None, default_weight=1, scale=1, center=None, seed=None, /)#

Position nodes using Fruchterman-Reingold force-directed algorithm.

The algorithm simulates a force-directed representation of the network treating edges as springs holding nodes close, while treating nodes as repelling objects, sometimes called an anti-gravity force. Simulation continues until the positions are close to an equilibrium.

  • graph (PyGraph) – Graph to be used.

  • pos (dict) – Initial node positions as a dictionary with node ids as keys and values as a coordinate list. If None, then use random initial positions. (default=None)

  • fixed (set) – Nodes to keep fixed at initial position. Error raised if fixed specified and pos is not. (default=None)

  • k (float) – Optimal distance between nodes. If None the distance is set to \(\frac{1}{\sqrt{n}}\) where \(n\) is the number of nodes. Increase this value to move nodes farther apart. (default=None)

  • repulsive_exponent (int) – Repulsive force exponent. (default=2)

  • adaptive_cooling (bool) – Use an adaptive cooling scheme. If set to False, a linear cooling scheme is used. (default=True)

  • num_iter (int) – Maximum number of iterations. (default=50)

  • tol (float) – Threshold for relative error in node position changes. The iteration stops if the error is below this threshold. (default = 1e-6)

  • weight_fn – An optional weight function for an edge. It will accept a single argument, the edge’s weight object and will return a float which will be used to represent the weight of the edge.

  • default_weight (float (default=1)) – If weight_fn isn’t specified this optional float value will be used for the weight/cost of each edge

  • scale (float|None) – Scale factor for positions. Not used unless fixed is None. If scale is None, no re-scaling is performed. (default=1.0)

  • center (list) – Coordinate pair around which to center the layout. Not used unless fixed is None. (default=None)

  • seed (int) – An optional seed to use for the random number generator


A dictionary of positions keyed by node id.

Return type: