com.yworks.yfiles.layout.hierarchic

Class WeightedLayerer

java.lang.Object

com.yworks.yfiles.layout.hierarchic.WeightedLayerer

All Implemented Interfaces:

ILayerer

public class WeightedLayerer
extends Object
implements ILayerer

This class implements the layering phase of the HierarchicLayout (i.e., the assignment of the nodes to layers).

It first makes the directed graph acyclic. Then, it assigns the layers such that edge weights are respected. A weight defines a minimum distance between the two end points of an edge.

Field Summary

Fields

Modifier and Type	Field and Description
protected Object	key The key to access the IDataProvider that holds the edge weights.
protected IDataProvider	weight This is a IDataProvider that holds for each Edge an integer value representing its weight.

Constructor Summary

Constructors

Constructor and Description
WeightedLayerer() Creates an instance of WeightedLayerer with the given key that provides access to the IDataProvider that holds the edge weights and unlimited maximum duration for the WeightedLayerer.
WeightedLayerer(Object key) Creates an instance of WeightedLayerer with the given key that provides access to the IDataProvider that holds the edge weights and unlimited maximum duration for the WeightedLayerer.

Method Summary

Modifier and Type	Method and Description
int	assignLayers(Graph graph, INodeMap layerID) Assigns all nodes of the graph to layers.
void	assignLayers(LayoutGraph graph, ILayers layers, ILayoutDataProvider ldp) Assigns all nodes of the graph to layers and adds them to the ILayers instance.
int	assignLayersFast(Graph graph, INodeMap layerID) Assigns all nodes of the graph to layers.
int	assignNodeLayer(LayoutGraph graph, INodeMap layerID, EdgeList reversedEdges) Assigns all nodes of the graph to layers.
int	assignNodeLayer(LayoutGraph graph, INodeMap layerID, EdgeList reversedEdges, IDataProvider weight) Assigns all nodes of the graph to layers.
long	getMaximumDuration() Gets the time limit in milliseconds set for the layout algorithm.
protected double	getWeight(Edge edge) Returns the edge weight of the given edge using the weight based cycle removal heuristic.
boolean	isWeightedCycleRemovalEnabled() Gets whether or not the edges that need to be reversed are determined using an edge weight based heuristic or using a depth first search based approach.
void	makeDFSAcyclic(Graph graph, EdgeList reversedEdges) Removes cycles from the graph using a depth first search.
void	setMaximumDuration(long value) Sets the time limit in milliseconds set for the layout algorithm.
void	setWeightedCycleRemovalEnabled(boolean value) Sets whether or not the edges that need to be reversed are determined using an edge weight based heuristic or using a depth first search based approach.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

key

protected Object key

The key to access the IDataProvider that holds the edge weights.

More precisely, the corresponding IDataProvider maps each edge of the input graph to an integer value representing the edge's weight.

weight

protected IDataProvider weight

This is a IDataProvider that holds for each Edge an integer value representing its weight.

Constructor Detail

WeightedLayerer

public WeightedLayerer()

Creates an instance of WeightedLayerer with the given key that provides access to the IDataProvider that holds the edge weights and unlimited maximum duration for the WeightedLayerer.

WeightedLayerer

public WeightedLayerer(Object key)

Creates an instance of WeightedLayerer with the given key that provides access to the IDataProvider that holds the edge weights and unlimited maximum duration for the WeightedLayerer.

Parameters:

key - the key to access the IDataProvider that holds the edge weights

Method Detail

assignLayers

public int assignLayers(Graph graph,
                        INodeMap layerID)

Assigns all nodes of the graph to layers.

Postcondition:

For all (v,w) in E: layer(v) < layer(w)

Parameters:

graph - the graph for which the layers are determined

layerID - the INodeMap that will be filled by the layout algorithm and returns the zero-based index of the layer to which each node belongs

Returns:

the number of layers

assignLayers

public void assignLayers(LayoutGraph graph,
                         ILayers layers,
                         ILayoutDataProvider ldp)

Assigns all nodes of the graph to layers and adds them to the ILayers instance.

Specified by:

assignLayers in interface ILayerer

Parameters:

graph - the input graph

layers - the ILayers instance that will be filled with the results of the calculation

ldp - the ILayoutDataProvider used for querying information about the nodes and edges

See Also:

ILayers.insert(com.yworks.yfiles.layout.hierarchic.LayerType, int), ILayer.add(com.yworks.yfiles.algorithms.Node)

assignLayersFast

public int assignLayersFast(Graph graph,
                            INodeMap layerID)

Assigns all nodes of the graph to layers.

Postcondition:

For all (v,w) in E: layer(v) < layer(w)

Parameters:

graph - the graph for which the layers are determined

layerID - the INodeMap that will be filled by the layout algorithm and returns a zero-based layer index for each node

Returns:

the number of layers

assignNodeLayer

public int assignNodeLayer(LayoutGraph graph,
                           INodeMap layerID,
                           EdgeList reversedEdges)

Assigns all nodes of the graph to layers.

Postcondition:

For all (v,w) in E: layer(v) < layer(w)

Parameters:

graph - the graph for which the layers are determined

layerID - the INodeMap that will be filled by the layout algorithm and returns the zero-based index of the layer to which each node belongs

reversedEdges - an EdgeList containing the edges which had been reversed

Returns:

the number of layers

assignNodeLayer

public int assignNodeLayer(LayoutGraph graph,
                           INodeMap layerID,
                           EdgeList reversedEdges,
                           IDataProvider weight)

Assigns all nodes of the graph to layers.

Postcondition:

For all (v,w) in E: layer(v) < layer(w)

Parameters:

graph - the graph for which the layers are determined

layerID - the INodeMap that will be filled by the layout algorithm and returns a zero-based layer index for each node

reversedEdges - an EdgeList containing the edges which had been reversed

weight - the IDataProvider that returns an integer value (weight) for each edge

Returns:

the number of layers

getMaximumDuration

public long getMaximumDuration()

Gets the time limit in milliseconds set for the layout algorithm.

Values have to be greater than or equal to 0.

Throws:

IllegalArgumentException - if the maximum duration is negative

Restricting the maximum duration may result in a lower layout quality. Furthermore, the real runtime may exceed the maximum duration since the layout algorithm still has to find a valid solution.

Default Value:

The default value is Long.MAX_VALUE. The layout algorithm runs unrestricted.

Returns:

a non-negative value that specifies the time limit

See Also:

setMaximumDuration(long)

getWeight

protected double getWeight(Edge edge)

Returns the edge weight of the given edge using the weight based cycle removal heuristic.

By default, all edges are considered to have weight 1.0.

It may be overridden if non-uniform weights are desired.

Parameters:

edge - given edge

Returns:

the edge weight of the specified edge

See Also:

isWeightedCycleRemovalEnabled(), setWeightedCycleRemovalEnabled(boolean)

isWeightedCycleRemovalEnabled

public boolean isWeightedCycleRemovalEnabled()

Gets whether or not the edges that need to be reversed are determined using an edge weight based heuristic or using a depth first search based approach.

The weight based approach may result in fewer reversed edges (especially for cases with many multi-edges) whereas the DFS based approach is likely to be faster.

Default Value:

The default value is false. The DFS based approach is used.

Returns:

true if an edge weight based heuristic is used; false if a DFS based approach is used

See Also:

setWeightedCycleRemovalEnabled(boolean)

makeDFSAcyclic

public void makeDFSAcyclic(Graph graph,
                           EdgeList reversedEdges)

Removes cycles from the graph using a depth first search.

Parameters:

graph - the graph

reversedEdges - an EdgeList containing the edges which will be reversed

setMaximumDuration

public void setMaximumDuration(long value)

Sets the time limit in milliseconds set for the layout algorithm.

Values have to be greater than or equal to 0.

Throws:

IllegalArgumentException - if the maximum duration is negative

Restricting the maximum duration may result in a lower layout quality. Furthermore, the real runtime may exceed the maximum duration since the layout algorithm still has to find a valid solution.

Default Value:

The default value is Long.MAX_VALUE. The layout algorithm runs unrestricted.

Parameters:

value - a non-negative value that specifies the time limit

See Also:

getMaximumDuration()

setWeightedCycleRemovalEnabled

public void setWeightedCycleRemovalEnabled(boolean value)

Sets whether or not the edges that need to be reversed are determined using an edge weight based heuristic or using a depth first search based approach.

The weight based approach may result in fewer reversed edges (especially for cases with many multi-edges) whereas the DFS based approach is likely to be faster.

Default Value:

The default value is false. The DFS based approach is used.

Parameters:

value - true if an edge weight based heuristic is used; false if a DFS based approach is used

See Also:

isWeightedCycleRemovalEnabled()