Graph Attributes  

This section describes the whole list of graph attributes. Each attribute is listed together with its type, default value and where it can be used, i.e. in the top-level graph, a subgraph specification or in both.

• amax   
  Type: integer
  Default value: automatic
  Attribute of: top-level graph
  Description:
  This attribute specifies the number of iterations that are animated after relayout. Specifying 0 means animation is turned off. This value can be changed interactively in the View dialog box (see general parameters).

• arrow_mode   
  Type: fixed, free
  Default value: fixed
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute specifies two modes for drawing arrow heads.
  • fixed  
    This arrow mode should be used if port sharing (see port_sharing) is used because then only a fixed set of rotations for the arrow heads are used. Here the arrow head is rotated only in increments of 45 degrees, and only one arrow head occurs at each port.
  • free  
    Here each arrow head is rotated individually for each edge. If a node has many incoming edges, this parameter can lead to a confusing image.

• attraction   
  Type: integer
  Default value: 60
  Attribute of: top-level graph
  Description:
  This attribute applies only to the forcedir layout algorithm.

  Here it is part of the force-directed spring embedder during attractive impulse calculation. It specifies the constant proportional to the attractive forces acting on a node.

  This constant and its repulsive counterpart (see repulsion) enable the length of edges to be controlled. For example, if only attractive and repulsive forces are working on a node, an edge length of n pixels is achieved for edges with priority of 1 (see edge attribute priority) by specifying n² for the attributes attraction and repulsion. Usually the values for these two attributes are of the same order of magnitude.

  For details, see force-directed layout.

• bmax   
  Type: integer
  Default value: 100
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute sets the maximum number of iterations of the phase reducing edge bends. Edge bends are used to prevent edges from being drawn across nodes. Reducing the number of iterations reduces layout calculation time, however the layout quality may suffer.

• border   
  Type:
       x : integer pixels or
       y : integer pixels
  Default value: x : 600, y : 600
  Attribute of: top-level graph
  Description:
  This attribute applies only to the forcedir layout algorithm.

  Depending on the specification of the layout parameters for the forcedir layout algorithm it is possible for nodes to move far away from one another (especially single nodes not connected to the main graph) This prevents nodes from being placed ``infinitely'' far from one another.

  These two attributes enable a rectangle to be specified within which the graph is drawn.

  For details, see force-directed layout.

• bordercolor   
  Type: black, blue, red, ...
  Default value:
        Same as the value of the textcolor attribute for summary nodes
  Attribute of: subgraphs
  Description:
  Specifies the color for borders of summary nodes, boxes and frames of clusters. For details on colors, see section Colors. See also color and textcolor attribute.

• borderstyle   
  Type: continuous, dashed, dotted, double, invisible, solid, triple
                Default value: continuous
  Attribute of: subgraphs
  Description:
  This attribute specifies the line style used for drawing the borders of a summary node. See also edge attribute linestyle.

• borderwidth   
  Type: integer
  Default value: 2 pixels
  Attribute of: subgraphs
  Description:
  This attribute specifies the thickness of the border of a summary node in pixels.

• classname   
  Type: integer : string
  Default value: 1 : ``1'', 2 : ``2'', 3 : ``3'', ...
  Attribute of: top-level graph
  Description:
  This attribute enables the names of edges classes to be introduced. These names appear in the Select Edge Classes dialog box. For details on edge classes, see edge classes.

• cmin, cmax      
  Type: integer
  Default value: 0 for cmin, infinite for cmax
  Attribute of: top-level graph, subgraphs
  Description:
  The cmin attribute sets the minimum number of iterations that are performed for reducing crossings using crossing weights. The normal method stops when two consecutive checks no longer cause the number of crossings to be reduced. However, this number of crossings might be a local minimum, meaning the number of crossing might decrease even more after some more iterations.

  The cmax attribute sets the maximum number of iterations of the crossing reduction phase. A reduction of this value causes the layout process to be speeded up. The default value infinite means that the method is iterated as long as any improvement is possible.

• color   
  Type: black, blue, red, ...
  Default value:
       white for top-level graph
       white for subgraphs
  Attribute of: top-level graph, subgraphs
  Description:
  • top-level graph
    Here the color attribute specifies the background color of the graph window.
  • subgraphs
    Here it specifies the background color of subgraphs. This color is valid as the background color in summary nodes, boxes, clusters and as a wrapping color.
  For details on colors, see section Colors. See also attributes textcolor and bordercolor.

• colorentry   
  Type: integer : integer integer integer
  Default value: no default value defined
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute enables the default color map to be filled and changed. A color is a triple of integer values for the red, green and blue part. Each integer ranges from 0 (color part turned off) to 255 (color part turned on), e.g. 0 0 0 specifies the color black and 255 255 255 specifies the color white. For instance, colorentry 75 : 70 130 180 sets map entry 75 to steel blue. This color can be used by merely specifying 75 wherever a color value is expected. For more details on colors, see colors.

• crossing_optimization   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph, subgraphs
  Description:
  yes activates the crossing optimization phase, which works locally. It is a postprocessing phase after normal crossing reduction. It tries to optimize locally by exchanging pairs of nodes to reduce the number of crossings.

• crossing_phase2   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph, subgraphs
  Description:
  yes activates crossing reduction phase two. In this phase, nodes having equal crossing weights are permuted. Note that this is the most time-consuming phase of crossing reduction.

• crossing_weight    
  Type: bary, median, barymedian, medianbary
  Default value: bary
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute specifies the weight to be used for crossing reduction. There is no general recommendation as to which is the best method. A guideline might be to use bary if the degree of the nodes is large and median or one of the hybrid methods barymedian or medianbary if the degree is small, the degree of a node being the total of incoming and outgoing edges at a node. See Crossing Reduction for details.
  • bary   
    The barycenter is used for calculating the weights during crossing reduction. This is the fastest method for graphs with nodes whose average degree is very large.
  • median    
    The median center is used for calculating the weights during crossing reduction.
  • barymedian  
    These weights are the combination of barycenter and mediancenter weights, with barycenter having priority and mediancenter only being used for nodes whose barycenter weights are equal.
  • medianbary  
    These weights are the combination of barycenter and mediancenter weights, with the mediancenter having priority.

• dirty_edge_labels  
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes forces a fast layout of edge labels, which may result in overlapping of labels. Dirty edge labels cannot be used if splines are used for edge drawing.

• display_edge_labels   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes: edge labels are displayed, no: edge labels are not displayed.

• edges   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph
  Description:
  no: suppresses the drawing of edges in the top-level graph and in all nested subgraphs.

• energetic   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph
  Description:
  This attribute applies only to the forcedir layout algorithm.

  Apart from the forces of the spring embedder and the magnetic fields, the local energy level of a node can be taken into account in deciding whether the node should move or not. Setting this attribute to yes causes the local energy present at a node to be considered during layout.

  For details, see force-directed layout.

• energetic attraction, energetic repulsion, energetic gravity,
  energetic crossing, energetic overlapping, energetic border                  
  Type: float
  Default values: see list below
  Attribute of: top-level graph
  Description:
  This attribute applies only to the forcedir layout algorithm.

  Apart from the forces of the spring embedder and the magnetic fields, the local energy level of a node can be taken into account in deciding whether the node should move or not. The behavior of the local energy present at a node can be influenced via the following attributes:

  • energetic attraction, Default value: 70.0
    Weight of the attractive energy of edges
  • energetic repulsion, Default value: 70.0
    Weight of the repulsive energy between nodes
  • energetic gravity, Default value: 0.3
    Weight of the gravitational energy of a node
  • energetic crossing, Default value: 80.0
    Weight of the global energy of an edge crossing
  • energetic overlapping, Default value: 80.0
    Weight of the global energy of a node overlapping
  • energetic border, Default value: 70.0
    Weight of the border energy of a node

  Gauging layout quality can be done as follows: The better the layout, the lower the total of all the energy values mentioned above.

  For details, see force-directed layout.

• equal_y_dist   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  If this attribute is enabled (yes), then the vertical distance in a hierarchical layout is equal among all levels.

• fast_icons   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph
  Description:
  yes: causes icon file loading to be faster, which may negatively impact the quality of the drawing if not all the icon colors are present. For details on pictures in nodes, see icons.

• fdmax   
  Type: integer
  Default value: 300
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Here it is used in the simulated annealing part of the algorithm. It specifies the upper hard limit for the number of iterations performed. The algorithm stops when the global temperature drops below a threshold value or when the limit specified here is reached.

  For details, see force-directed layout.

• finetuning   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph, subgraphs
  Description:
  no: switches off the fine-tuning phase of the graph layout algorithm. The fine-tuning phase tries to give all edges the same length. It tries to improve the ranks of nodes in order to avoid very long edges (see assignment of ranks).

• focus   
  Type: no type
  Default value: no value
  Attribute of: subgraphs
  Description:
  This attribute sets the focus for the summary node of a subgraph, i.e. if the status of the subgraph is folded at startup, then the summary node of the subgraph for which focus was specified is centered in the graph window.

  Note: The focus can also be specified for nodes (see node attribute focus). It goes without saying that the focus attribute should appear only once in a graph specification.

• fontname   
  Type: string
  Default value: default font drawn by turtle graphics routines
  Attribute of: subgraphs
  Description:
  This attribute specifies a pixel font different from the default font and used for drawing the text labels of summary nodes. This font is given by the name of the aiSee font file containing the font description, e.g. a 12-point Times Roman font can be specified via fontname: "timR12.vcf". Note: If the font file is not in the current directory the environment variable AISEEFONTS has to be set to the directory containing the font description files.   For details on fonts, see additional fonts.

• fstraight_phase   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph
  Description:
  yes: forces straight edges that are not anchored at the same position on the border of the nodes. This is useful only if no port sharing is selected, because bends are avoided by correcting the port position.

• gravity   
  Type: float
  Default value: 0.0625
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  It is used for impulse calculation. Only using a simulation of a spring embedder would force unconnected components of a graph to move further and further apart from one another, as there would be no attractive forces acting between them. That is why gravity is introduced as a counterforce.

  This attribute specifies the constant which is proportional to the gravitational force acting on a node. This constant controls the strength of the gravitational force, e.g. a value of zero cancels out the influence of any gravitational force.

  For details, see force-directed layout.

• height   
  Type: integer
  Default value:
       Top-level graph: (height of root screen - 100) pixels
       Subgraphs: (height of the label for summary nodes) pixels
  Attribute of: top-level graph, subgraphs
  Description:
  The meaning of this attribute depends on where it is specified:
  • top-level graph
    This attribute specifies the height of the display window in pixels.
  • subgraphs
    Here it specifies the height of the summary node.
  See also graph attribute width.

• hidden   
  Type: integer
  Default value: none
  Attribute of: top-level graph
  Description:
  This attribute specifies the edge class to be hidden. To hide more than one edge class, repeat this attribute for each additional edge class. For more details, see edge classes.

  Edges in such a class are ignored during layout calculation and are not drawn. Nodes that are only accessible (forward or backward) via edges of a hidden class are not drawn. However, nodes that are not accessible at all are drawn (see ignore_singles).

  Note the difference between hiding edge classes and the edge line style invisible. Hidden edges do not exist in the layout. Edges with the invisible line style exist in the layout, i.e. they influence the layout, meaning they need space and may produce crossings, for example.

• horizontal_order   
  Type: integer
  Default value: none (corresponds to -1)
  Attribute of: subgraphs
  Description:
  In a hierarchical layout, this attribute specifies the horizontal position of the summary node within a level (see vertical_order). The nodes specified via horizontal positions are ordered according to these positions within the levels. Nodes without this attribute are inserted into this ordering by the crossing reduction mechanism (see crossing reduction).

  Note: Connected components are handled separately during crossing reduction, thus it is not possible to intermix nodes of different connected components in one ordering sequence. For example, one connected component consists of nodes A, B, C and another of nodes D, E, all nodes being positioned at the same level. Thus, for instance, it is not possible to specify the following horizontal order at level 0: A, D, C, E.

  Note further: If the algorithm for downward laid-out trees is used the specified horizontal order is retained only within nodes that are children of the same node, i.e. in case of downward laid-out trees it is not possible to specify a horizontal order for the entire level.

• iconcolors   
  Type: integer
  Default value: 32
  Attribute of: top-level graph
  Description:
  This attribute specifies the size of the color map used for colors in bitmap files. For details on pictures in nodes, see icons.

• iconfile   
  Type: string
  Default value: no default value
  Attribute of: subgraphs
  Description:
  This attribute specifies the bitmap file (format raw PBM, PPM) to be displayed in the summary node of the folded subgraph. Note: if the bitmap file to be displayed is not in the current directory the environment variable AISEEICONS can be set to the directory containing the bitmap file.   For details on pictures in nodes, see icons.

• icons   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph
  Description:
  no: disables displaying of icons in nodes. Displaying of icons can be enabled again interactively from the View dialog box.

• ignore_singles   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes: hides all nodes of the remaining graph which would appear singly and unconnected. These nodes have no edges at all and drawing them sometimes results in an ugly layout of the remaining graph. The default setting is to show all nodes (no option).

• importance   
  Type: integer
  Default value: 0 (which means infinity)
  Attribute of: subgraphs
  Description:
  This is the central attribute when it comes to filtering in fish-eye views as it enables the importance of a summary node of a folded subgraph to be specified via an integer.

  Low integers signify less important nodes which are filtered out first by a filtering fish-eye view. High integer numbers signify nodes that are important, their being rarely filtered out. A value of 0 represents an infinite importance, the result being that these nodes are never filtered out. This attribute exists for nodes too, see importance.

• info1, info2, info3       
  Type: string
  Default value: empty string for all three
  Attribute of: subgraphs
  Description:
  These attributes enable three additional text fields to be specified for a summary node of a folded subgraph. The same set of attributes exists for nodes (see node attribute info1). These additional information fields can be selected interactively from the submenu of the Information menu.

• inport_sharing
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  See graph attribute port_sharing.

• invisible   
  Type: integer
  Default value: no default value
  Attribute of: top-level graph
  Description:
  This attribute is a synonym for the graph attribute hidden.

• label   
  Type: string
  Default value: empty string
  Attribute of: subgraphs
  Description:
  This string is displayed inside the summary node of a folded subgraph. If no label is specified the value of the title of the subgraph is used. If there is no label or title specified for the subgraph then the file name of the graph specification file is used.

  Note: This text may contain control characters, e.g. ``\n'' (newline character), that influence the size of the node. See character set for more details.

• infoname   
  Type: integer : string
  Default value: 1 : ``0'', 2 : ``1'', 3 : ``2''
  Attribute of: top-level graph
  Description:
  This attribute enables names for the additional information fields available for each node to be introduced. These names appear in the submenu of the menu item Information   in the Misc menu of the menu line. For details on additional information fields, see section Information and info1.

• late_edge_labels   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute controls the moment when edge labels are drawn.
  • yes
    The graph is first partitioned and then edge labels are introduced.
  • no
    In this case the algorithm first creates labels and then partitions the graph. This option yields a more compact layout, but may result in more crossings.

• layoutalgorithm    
  Type: normal, maxdepth, mindepth, ...
  Default value: normal
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute specifies the basic layout algorithms, there being two main categories. The first fourteen algorithms describe variations of a hierarchical layout, whereas the last algorithm implements a force-directed layout. The variations differ in the way nodes are selected for the various levels in the hierarchical layout.
  • normal  
    This algorithm is the default algorithm. It tries to give all edges the same orientation and is based on the calculation of strongly connected components. The algorithms based on depth first search are faster.

  • dfs  
    This algorithm uses a depth first search for layout calculation, but does not enforce additional constraints pertaining to the degree of nodes. It is faster than the normal layout algorithm. The result is heavily dependent on the initial order of the nodes in the specification.

  • maxdepth/mindepth    
    These two algorithms are based on depth first search and are both fast heuristics. maxdepth tries to increase the depth of the layout. mindepth tries to increase the width of the layout.

  • maxdepthslow / mindepthslow     
    These slower algorithms might be better if the fast heuristics offered by the algorithms maxdepth and maxdepth do not provide satisfying results. maxdepthslow tries to increase the depth of the layout and mindepthslow the width of the layout.

  • maxindegree / minindegree     
    maxindegree schedules nodes with a maximum of incoming edges first, i.e. these nodes are positioned early. minindegree schedules nodes with a minimum of incoming edges first.

  • maxoutdegree / minoutdegree     
    maxoutdegree schedules nodes with a maximum of outgoing edges first, i.e. these nodes are positioned early. minoutdegree schedules nodes with a minimum of outgoing edges first.

  • maxdegree / mindegree     
    maxoutdegree schedules nodes with a maximum of the sum of incoming and outgoing edges first, i.e. these nodes are positioned early. The algorithm minoutdegree schedules nodes with the minimum of the sum of incoming and outgoing edges first.

  • minbackward   
    Instead of calculating strongly connected components, minbackward performs a topological sorting to assign ranks to the nodes. This algorithm is fast if the graph is acyclic.

  • tree   
    The tree algorithm is a specialized method for downward laid out trees. It is very fast for these tree-like graphs and results in a balanced layout.

  • forcedir   
    This layout algorithm computes a force-directed placement. It is a nonhierarchical layout method that works well for undirected graphs. Some features of hierarchical layout like near edges are disabled for this layout algorithm.

    The layout calculation for this algorithm can be controlled via the following graph attributes:

    • Spring embedder forces
      attraction, repulsion

    • Gravitational forces
      gravity

    • Simulated annealing
      fdmax
      tempmin, tempmax
      temptreshold, tempscheme, tempfactor

    • Random influence
      randomfactor, randomrounds, randomimpulse

    • Magnetic forces
      magnetic_field1, magnetic_field2
      magnetic_force1, magnetic_force2

    • Energy level
      energetic
      energetic attraction, energetic repulsion
      energetic gravity, energetic crossing
      energetic overlapping, energetic border

    • Boundary rectangle
      border x, border y

• layout_downfactor, layout_upfactor, layout_nearfactor         
  Type: integer
  Default value: 1 for all three attributes
  Attribute of: top-level graph, subgraphs
  Description:
  The layout algorithm partitions the set of edges into edges pointing upward, edges pointing downward, and edges pointing sidewards. The last type of edges is also called near edges. These attributes have no effect if the layout algorithm tree is used.

  If the layout_downfactor is large as compared to the layout_upfactor and layout_nearfactor, then the positions of the nodes are mainly determined by the edges pointing downwards.

  If the layout_upfactor is large as compared to the layout_downfactor and layout_nearfactor, then the positions of the nodes are mainly determined by the edges pointing upwards.

  If the layout_nearfactor is large, then the positions of the nodes are mainly determined by the edges pointing sidewards.

• level   
  Type: integer
  Default value: none (corresponds to -1)
  Attribute of: subgraphs
  Description:
  This attribute is a synonym for vertical_order.

• linear_segments   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes switches linear segment layout on. This layout favors straight long vertical edges. See also -linseg and -linsegmax.

• loc   
  Type: { x: <integer> y: <integer> }
  Default value:
       Top-level graph: { x:0 y:0 } for both
       Subgraphs: unspecified for both
  Attribute of: top-level graph, subgraphs
  Description:
  For details, see x.

• magnetic_field1, magnetic_field2      
  Type:
       no, top_to_bottom,   bottom_to_top,   left_to_right,   right_to_left,
         polar,   circular,   orthogonal,   polcircular
    Default value: no
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Magnetic fields are part of impulse calculation. Forces that originate from a simulation of a spring embedder neglect the directions of edges. In directed graphs edges should point in a uniform direction, consequently magnetic forces are introduced, with edges being interpreted as magnetic needles that align according to a magnetic field.

  Two independent magnetic fields are possible. These two attributes specify the kind of magnetic field for each. If two fields are specified, the edges are influenced by both. The attributes magnetic_force1 and magnetic_force2 influence the strength of each field.

  For details, see force-directed layout.

• magnetic_force1, magnetic_force1      
  Type: integer
  Default value: 1 for both
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  These two attributes specify the constant factors that are multiplied by the corresponding magnetic forces of the two magnetic fields.

  See also magnetic_field1 and magnetic_field2.

  For details, see force-directed layout.

• manhattan_edges   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes switches orthogonal layout on. Orthogonal layout (or Manhattan layout) means that all edges consist of horizontal or vertical line segments. Vertical edge segments might be shared by several edges, while horizontal edge segments are never shared. This results in aesthetic layouts for flowcharts. If orthogonal layout is used, the priority phase and straight phase are also used by default (see priority_phase and straight_phase).

• near_edges   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph, subgraphs
  Description:
  no: All near edges are treated as normal edges in the graph layout.

• nodes   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph
  Description:
  no: Suppresses the drawing of nodes in the top-level graph and all nested subgraphs.

• node_alignment   
  Type: top, center, bottom
  Default value: center
  Attribute of: top-level graph, subgraphs
  Description:
  For hierarchical layout this attribute specifies the vertical alignment of nodes at the horizontal reference line of levels.
  • top:   The tops of all nodes of a level have the same y coordinate.
  • center:   All nodes of a level are centered.
  • bottom:   The bottoms of all nodes of a level have the same y coordinate.

• orientation   
  Type: top_to_bottom,   bottom_to_top,   left_to_right,   right_to_left
    Default value: top_to_bottom
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute specifies the orientation of the graph. All explanations in this section are given in relation to the default orientation.

• outport_sharing
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  See graph attribute port_sharing.

• pmin, pmax      
  Type: integer
  Default value:
       0 for pmin
       100 for pmax
  Attribute of: top-level graph, subgraphs
  Description:
  pmin sets the minimum number of iterations of the pendulum method. Like crossing reduction, this method stops when the ``imbalance weight'' stops decreasing. However, an increase in imbalance weight might be a local phenomenon, meaning that the imbalance might decrease much more after a few more iterations.

  pmax sets the maximum number of iterations of the pendulum method. Reducing this factor increases layout calculation speed.

• port_sharing, inport_sharing, outport_sharing         
  Type: yes, no
  Default value:
       yes for port_sharing,
       no for inport_sharing and outport_sharing
  Attribute of: top-level graph, subgraphs
  Description:
  no suppresses the sharing of ports by edges at nodes. inport_sharing enables the port sharing of incoming edges only, with outport_sharing enabling the port sharing of outgoing edges only.

  Generally speaking, if multiple edges are adjacent to the same node, and the arrow heads of all these edges have the same appearance (color, size, etc.), these edges may share a port at a node. This means that only one arrow head is drawn, and all edges meet at this arrow head. This enables many edges to be located adjacent to one node without getting confused by too many arrow heads. If no port sharing is used, each edge gets its own port.

• priority_phase   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes switches on the priority phase. This phase replaces the normal pendulum method with a specialized method: It forces long vertical edges to be straight, just like the straight phase. In fact, the straight phase is a fine-tuning of the priority phase, the priority phase being recommended for an orthogonal layout (see manhattan_edges).

• randomfactor   
  Type: integer
  Default value: 70
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  If randomized rounds have been specified (see randomrounds) then a node is placed with a probability of randomfactor percent during a round. This factor should be close to 100 in order to prevent the process from stopping too early.

  For details, see force-directed layout.

• randomimpulse   
  Type: integer
  Default value: 32
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  It specifies the strength of the random impulse vector. If the forcedir algorithm should behave like a simulated annealing algorithm, this constant should be large and a slow temperature scheme should be chosen. Otherwise a small value is preferable for the randomimpulse attribute.

  For details, see force-directed layout.

• randomrounds   
  Type: integer
  Default value: -1
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  This attribute specifies the number of randomized rounds during impulse calculation. It should only be used for the first few rounds so as to add a random impulse. Afterwards, the random impulse would delay completion of calculation.

  For details, see force-directed layout.

• repulsion   
  Type: integer
  Default value: 60
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Here it is part of the force-directed spring embedder during repulsive impulse calculation. It specifies the constant that is inversely proportional to the attractive forces acting on a node.

  This constant and its attractive counterpart (see attraction) enabled the length of edges to be controlled. Usually the values for these two attributes are of the same order of magnitude.

  For details, see force-directed layout.

• rmin, rmax      
  Type: integer
  Default value:
  0 for rmin
  100 for rmax
  Attribute of: top-level graph, subgraphs
  Description:
  rmin sets the minimum number of iterations for rubberbanding. This works in a manner similar to the pendulum method.

  rmax sets the maximum number of iterations for rubberbanding. Reducing this factor increases layout calculation speed.

• scaling   
  Type: a float value or maxspect
  Default value: 1.0
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute specifies the scaling factor for graph representation. A scaling factor of 1.0 means normal size. maxspect scales a graph so that the entire graph fits into the graph window.  For details, see shrink.

• shape   
  Type:
       box, rhomboid, ellipse, circle, triangle,
       trapezoid, uptrapezoid, hexagon, lparallelogram, rparallelogram
                      Default value: box
  Attribute of: subgraphs
  Description:
  Specifies the shape of the summary node of a folded subgraph (see node attribute shape for a description of shapes).

• shrink, stretch      
  Type: integer
  Default value: 1 for both
  Attribute of: top-level graph, subgraphs
  Description:
  These two attributes specify the shrinking and stretching factors for the representation of the top-level graph. The scaling of the graph as a percentage is given by the formula ((stretch / shrink) * 100).

  For instance, (stretch, shrink) = (1, 1) or (2, 2) or (3, 3) or ... is normal size, (stretch, shrink) = (1, 2) is half size, and (stretch, shrink) = (2, 1) is double size. The scaling factor can also be specified via the scaling.

  • top-level graph
    When these attributes are specified for the top-level graph, they determine the size of the entire graph including all the subgraphs.
  • subgraphs
    When specified for a subgraph they determine the scaling factor of the summary node of the folded subgraph. The size of a boxed subgraph is not affected, however the size of the subgraph nodes may still be affected (for details, see node attribute shrink).

• smanhattan_edges   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes selects a specialized orthogonal layout: All horizontal edge segments between two levels share the same horizontal line, i.e. not only vertical edge segments are shared (as in the Manhattan layout). However, horizontal edge segments are shared by several edges, too. This looks nice for trees but might be confusing in general.

• smax   
  Type: integer
  Default value: 100
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute sets the maximum number of iterations of the straight-line recognition phase. This value is not of any use unless the straight-line recognition phase is switched on, see straight_phase. It can be used to improve the Manhattan layout or the layout with the priority phase turned on.

• splinefactor   
  Type: integer
  Default value: 70
  Attribute of: top-level graph
  Description:
  This factor determines the bending of splines. A factor of 100 indicates very sharp bending, a factor of 1 indicating very flat bending. Useful values range from 30 to 80.

• splines   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph
  Description:
  This attribute specifies whether splines are used to draw edges. Polygon segments are used to draw edges by default, because this is much faster. Note that the spline drawing routine is very slow. Splines are mainly used to prepare high-quality PostScript output for very small graphs.

• spreadlevel   
  Type: integer
  Default value: 1
  Attribute of: top-level graph, subgraphs
  Description:
  This parameter only influences the tree algorithm. Spreading of the uppermost nodes of large balanced trees would increase the width of the tree to such an extent that the tree would no longer fit in a window. Consequently, the spread level specifies the minimum level (rank) where nodes are spread. Nodes of levels above the spread level are not spread.

• state   
  Type: boxed, clustered, exclusive, folded, unfolded, wrapped,
  Default value: unfolded
  Attribute of: subgraphs
  Description:
  This attribute specifies the initial state of a subgraph, i.e. it describes the way a subgraph is displayed the first time a graph is visualized. The appearance of the subgraph (its state) can be changed interactively later on (see groups of nodes).
  • boxed   
    The subgraph is surrounded by a frame, i.e. drawn in a box. The nodes in side the box are independent of the rest of the graph, i.e. there are no edges connecting nodes outside the box with nodes inside the box and vice versa. For details, see box.
  • clustered   
    The subgraph is surrounded by a frame. In contrast to a box, edges from nodes outside the frame are drawn to nodes inside the frame and vice versa. This is an experimental feature. For details, see cluster.

  • exclusive   
    The subgraph is shown exclusively. All other nodes of the graph are not visible. Only edges between nodes of a group are visible. Of course, this value should appear only once in a graph specification. For details, see exclusive subgraphs.

  • folded   
    The nodes of a subgraph are hidden. They are represented by a single node, called a summary node. For details, see folding.

  • wrapped   
    All nodes and edges belonging to the subgraph are wrapped using the same color. For details, see wrapping.

• straight_phase   
  Type: yes, no
  Default value: no
  Attribute of: top-level graph, subgraphs
  Description:
  yes switches on the straight phase. This is an additional phase that tries to avoid bends in long edges. Long edges are drawn as long straight vertical lines. Thus, this phase is not very appropriate for normal layout, however it is recommended when an orthogonal layout is selected (see manhattan_edges).

• stretch
  Type: integer
  Default value: 1
  Attribute of: top-level graph, subgraphs
  Description:
  See graph attribute shrink.

• subgraph_labels   
  Type: yes, no
  Default value: yes
  Attribute of: top-level graph
  Description:
  no: Switches off the displaying of subgraph labels. This can also be done interactively from the View dialog box.

• tempfactor   
  Type: float
  Default value: 1.3
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  It is used in the simulated annealing part of the algorithm. It specifies the temperature scheme factor used for exponential and reverse exponential temperature schemes.

  For details, see force-directed layout.

• tempmin   
  Type: integer
  Default value: 1
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Here it is used in the simulated annealing part of the algorithm. It specifies the lower limit of the temperature range.

  For details, see force-directed layout.

• tempmax   
  Type: integer
  Default value: 128
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Here it is used in the simulated annealing part of the algorithm. It specifies the upper limit of the temperature range.

  For details, see force-directed layout.

• tempscheme   
  Type: integer
  Default value: 1
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  There are local and global temperature schemes. In global temperature schemes all nodes have the same temperature.

  • 1 (local temperature temp_speed)
    Local adaptive temperature scheme with speedup during cooling.
  • 2 (local temperature temp_normal)
    Local adaptive temperature scheme with no speedup.
  • 3 (global temperature temp_linear)
    Linear curve.
  • 4 (global temperature temp_hyperbolical)
    Hyperbolic curve: very fast descent, then a low temperature for an extended period of time
  • 5 (global temperature temp_exponential)
    Exponential descending temperature, i.e. a small temperature for an extended period of time.
  • 6 (global temperature temp_logarithmic)
    Logarithmic descending, i.e. a small temperature for an extended period of time.
  • 7 (global temperature temp_reverse_exponential)
    Reverse exponential descending temperature, i.e. a high temperature for an extended period of time.
  • 8 (global temperature temp_reverse_logarithmic)
    Reverse logarithmic descent, i.e. a high temperature for an extended period of time.

  For details, see force-directed layout.

• temptreshold   
  Type: integer
  Default value: 3
  Attribute of: top-level graph
  Description:
  This attribute only applies to the forcedir layout algorithm.

  Here it is used in the simulated annealing part of the algorithm. It specifies the threshold value for the global temperature. The algorithm stops if the global temperature drops below the value specified here.

  For details, see force-directed layout.

• textcolor   
  Type: black, blue, red, ...
  Default value:
       black for summary nodes
  Attribute of: subgraphs
  Description:
  Specifies the color for text labels of summary nodes. For details on colors, see section Colors. See also color and bordercolor.

• textmode   
  Type: center, left_justify, right_justify
        Default value: center
  Attribute of: subgraphs
  Description:
  This attribute specifies the alignment of text within a summary node frame.

• title   
  Type: string
  Default value: name of the graph specification file
  Attribute of: subgraphs
  Description:
  This attribute specifies the name associated with the subgraph. If no title is specified the name of the file containing the graph specification is used. Note: Titles have to be unique throughout a graph specification, meaning there can be only one subgraph at most without a title specification.

  The name of a subgraph is used to identify this graph, so that the subgraph can be the source and target of an edge specification. These edges start or end at the summary nodes of folded subgraphs. If the subgraph is visualized unfolded, these edges start or end at the root of the subgraph or at the root of the first subgraph in the subgraph.

• treefactor   
  Type: float
  Default value: 0.5
  Attribute of: top-level graph, subgraphs
  Description:
  The tree algorithm for downward laid-out trees tries to produce a medium dense balanced tree-like layout. If the tree factor is greater than 0.5, the tree edges are spread, i.e. they have a larger gradient, this possibly improving the readability of the tree. Note: It is not obvious whether spreading results in a denser or wider layout. A tree factor exists for each tree, enabling maximu density of the entire tree.

• useractioncmd1, useractioncmd2, useractioncmd3, useractioncmd4   
  Type: string
  Default value: empty string for all three
  Attribute of: top-level graph
  Description:
  These attributes enable four commands to be specified in a graph specification, that are executed when one of the User Action menu entries in the Auxiliaries menu is invoked by the user.

  For details on user actions, see section User Actions and also be refered to useractionname.

• useractionname   
  Type: integer : string
  Default value: 1 : ``User Action 1'', 2 : ``User Action 2'', 3 : ``User Action 3'',
  4 : ``User Action 4''
  Attribute of: top-level graph
  Description:
  This attribute enables names for the user actions menu entries in the Auxiliaries menu to be introduced.

  These names appear in the submenu of the menu item Auxiliaries   in the menu line. For details on user actions, see section User Actions and useractioncmd.

• vertical_order   
  Type: integer or maxlevel
  Default value: none (corresponds to -1)
  Attribute of: subgraphs
  Description:
  In a hierarchical layout, this attribute specifies the vertical position of a summary node of a folded subgraph. maxlevel   tries to position the node as the maximum calculated level. Generally for all nodes, their vertical position is called their level or rank (see rank assignment). level is a synonym for vertical_order.

  All nodes of level 0 form the uppermost layer (the first layer), if the orientation is top-down. Nodes of level 1 form the second layer, etc.

  The level specification is not in effect unless automatic layout is being calculated. Layout is calculated automatically if there is at least one node without a specified location (see loc attribute for nodes and summary nodes).

  Note: The level specification may conflict with a near edge specification, because the source and target node of a near edge have to have the same level. In this case, the level specification of the source or the target node of the near edge is ignored.

• view   
  Type: cfish, fcfish, dcfish, pfish, fpfish, dpfish
  Default value: normal view, i.e. no fish-eye view
  Attribute of: top-level graph
  Description:
  This attribute enables one of the six fish-eye views to be selected.

  If a graph is large only a small amount of it is visible in the graph window because of the fixed size of the window. Reducing the graph so that it fits into the window causes details to no longer be recognizable. The solution to this is fish-eye views. A fish-eye view is a coordinate transformation, causing the view of the graph to be distorted.

  There is a focus which is magnified so that all the details can be seen. Parts of the graph that are far away from the focus are scaled down.

  • cfish  
    Self-adaptable Cartesian fish-eye view. The effect of the Cartesian fish eye is similar to polar fish-eye view, only that the Cartesian coordinate system is transformed instead of the polar system. In this view horizontal and vertical lines remain horizontal and vertical after transformation, i.e. they are not bent as in the case of polar fish-eye view.
  • fcfish  
    Cartesian fish-eye view with a fixed radius. Here the fish eye only shows a fixed radius around the focus, meaning the entire graph may no longer be visible.
  • dcfish  
    Cartesian fish-eye view with a double focus.
  • pfish  
    Self-adaptable polar fish-eye view. The plane containing the graph layout is projected onto a sphere. Polar fish-eye view is a 3D look onto this sphere.
  • fpfish  
    Polar fish-eye view with a fixed radius. Here the fish-eye view only shows a fixed radius around the focus, meaning the entire graph may no longer be visible.
  • dpfish  
    Polar fish-eye view with a double focus.

• width   
  Type: integer
  Default value:
       Top-level graph: (width of root screen - 100) pixels
       Subgraphs: (width of the label for summary nodes) pixels
  Attribute of: top-level graph, subgraphs
  Description:
  The meaning of this attribute depends on its location.
  • top-level graph This attribute specifies the width of the display window in pixels.
  • subgraphs Here it specifies the width of the summary node in pixels.
  See also graph attribute height.

• x, y      
  Type: integer
  Default value:
       Top-level graph: 0 pixels for both
       Subgraphs: unspecified for both
  Attribute of: top-level graph, subgraphs
  Description:
  The meaning of these attributes differ depending on whether they are specified for the top-level graph or for subgraphs.
  • top-level graph
    Here these attributes specify the position of the graph window in relation to the root screen, i.e. the x and y coordinates of the upper left corner of the graph window are specified in pixels. The origin of the root screen is in the upper left corner.
  • subgraphs
    Here they specify the x and y coordinates (in pixels) of the summary node in relation to the upper left corner of the graph window.
  The positions can also be specified via the loc.

• xbase, ybase      
  Type: integer
  Default value: 5 pixels for both attributes
  Attribute of: top-level graph, subgraphs
  Description:
  xbase, ybase specify the horizontal and vertical offset between the graph window and the upper left-hand corner of the graph, i.e. the position of the origin of the coordinate system in relation to the upper left-hand corner of the virtual window.

  In subgraph specifications they are the offsets from the frame of the box containing the subgraph.

• xmax, ymax      
  Type: integer
  Default value:
        (width of the root screen - 90) pixels for xmax
        (height of the root screen - 90) pixels for ymax
  Attribute of: top-level graph
  Description:
  These attributes specify the maximum size of the virtual window used to display the graph (see Figure 26). This is usually larger than the displayed part. The width and height of the displayed part cannot be larger than xmax and ymax. Only the parts of the graph inside the virtual window are drawn. The virtual window can be moved over the potentially infinite coordinate system by special positioning commands (see navigation).

  Note: It is advisable to set xmax, ymax so they do not exceed the size of the root screen so as to get good performance.

     
  

    

  Figure 26: Displayed Window and Virtual Window

  
  

• xlspace   
  Type: integer
  Default value:
       1/2 xspace pixels, if polygons are used for edge drawing
       4/5 yspace pixels, if splines are used
  Attribute of: top-level graph, subgraphs
  Description:
  This attribute describes the horizontal distance between lines at the points where they cross levels. Note: It is advisable to set xlspace to a larger value, if splines are used in order to prevent sharp bends.

• xspace,yspace      
  Type: integer
  Default value:
       20 pixels for xspace,
       70 pixels for yspace
  Attribute of: top-level graph, subgraphs
  Description:
  xspace, yspace specify the minimum horizontal and vertical distance between nodes.