Class: Rubyvis::Layout::Network

Inherits:
Rubyvis::Layout show all
Defined in:
lib/rubyvis/layout/network.rb

Overview

Represents an abstract layout for network diagrams. This class provides the basic structure for both node-link diagrams (such as force-directed graph layout) and space-filling network diagrams (such as sunbursts and treemaps). Note that “network” here is a general term that includes hierarchical structures; a tree is represented using links from child to parent.

Network layouts require the graph data structure to be defined using two properties:<ul>

<li>nodes - an array of objects representing nodes. Objects in this array must conform to the pv.Layout.Network.Node interface; which is to say, be careful to avoid naming collisions with automatic attributes such as index and link_degree. If the nodes property is defined as an array of primitives, such as numbers or strings, these primitives are automatically wrapped in an object; the resulting object’s node_value attribute points to the original primitive value.

<p><li>links - an array of objects representing links. Objects in this array must conform to the pv.Layout.Network.Link interface; at a minimum, either source and target indexes or source_node and target_node references must be set. Note that if the links property is defined after the nodes property, the links can be defined in terms of this.nodes().

</ul>

<p>Three standard mark prototypes are provided:<ul>

<li>node - for rendering nodes; typically a pv.Dot. The node mark is added directly to the layout, with the data property defined via the layout’s nodes property. Properties such as strokeStyle and fillStyle can be overridden to compute properties from node data dynamically.

<p><li>link - for rendering links; typically a pv.Line. The link mark is added to a child panel, whose data property is defined as layout’s links property. The link’s data property is then a two-element array of the source node and target node. Thus, poperties such as strokeStyle and fillStyle can be overridden to compute properties from either the node data (the first argument) or the link data (the second argument; the parent panel data) dynamically.

<p><li>label - for rendering node labels; typically a pv.Label. The label mark is added directly to the layout, with the data property defined via the layout’s nodes property. Properties such as strokeStyle and fillStyle can be overridden to compute properties from node data dynamically.

</ul>Note that some network implementations may not support all three standard mark prototypes; for example, space-filling hierarchical layouts typically do not use a link prototype, as the parent-child links are implied by the structure of the space-filling node marks. Check the specific network layout for implementation details.

<p>Network layout properties, including nodes and links, are typically cached rather than re-evaluated with every call to render. This is a performance optimization, as network layout algorithms can be expensive. If the network structure changes, call #reset to clear the cache before rendering. Note that although the network layout properties are cached, child mark properties, such as the marks used to render the nodes and links, are not. Therefore, non-structural changes to the network layout, such as changing the color of a mark on mouseover, do not need to reset the layout.

See Also:

Direct Known Subclasses

Hierarchy

Defined Under Namespace

Modules: LinkAdd Classes: Link, Node

Instance Attribute Summary collapse

Attributes inherited from Panel

#_canvas, #children, #root

Attributes inherited from Mark

#_properties, #binds, #child_index, #parent, #proto, #root, #scale, #scene, #target

Instance Method Summary collapse

Methods inherited from Rubyvis::Layout

Cluster, Hierarchy, Network, Partition, Stack, Treemap, attr_accessor_dsl, #layout_build_implied, #layout_build_properties

Methods inherited from Panel

#add, #anchor, #bind, #build_instance, #children_inspect, defaults, #panel_build_implied, #to_svg, #type

Methods inherited from Bar

defaults, #type, #width

Methods inherited from Mark

#add, #anchor, #area, attr_accessor_dsl, #bar, #bind, #build, #build_instance, #context, #context_apply, #context_clear, #cousin, defaults, #delete_index, #dot, #event, #execute, #first, #image, index, #index, index=, #index=, #index_defined?, #instance, #instances, #label, #last, #layout_cluster, #layout_partition, #layout_partition_fill, #layout_stack, #layout_treemap, #line, #margin, #mark_anchor, #mark_bind, #mark_build_implied, #mark_build_instance, #mark_build_properties, #mark_extend, mark_method, #panel, #properties, properties, property_method, #property_value, #render, #rule, scene, scene=, #sibling, stack, stack=, #type, #wedge

Constructor Details

#initialize ⇒ Network

Returns a new instance of Network.



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# File 'lib/rubyvis/layout/network.rb', line 80

def initialize
  super
  @_id=Rubyvis.id()
  @node=_node
  @link=_link
  @node_label=_node_label
end

Instance Attribute Details

#_id ⇒ Object

Returns the value of attribute _id.



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# File 'lib/rubyvis/layout/network.rb', line 79

def _id
  @_id
end

#link ⇒ Object

Returns the value of attribute link.



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# File 'lib/rubyvis/layout/network.rb', line 78

def link
  @link
end

#node ⇒ Object

Returns the value of attribute node.



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# File 'lib/rubyvis/layout/network.rb', line 78

def node
  @node
end

#node_label ⇒ Object

Returns the value of attribute node_label.



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# File 'lib/rubyvis/layout/network.rb', line 78

def node_label
  @node_label
end

Instance Method Details

#_link ⇒ Object

The link prototype, which renders edges between source nodes and target nodes. This prototype is intended to be used with a Line mark in conjunction with the node prototype.



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# File 'lib/rubyvis/layout/network.rb', line 115

def _link
  that=self
  l=Mark.new().
    mark_extend(@node).
    data(lambda {|d| [d.source_node, d.target_node] }).
    fill_style(nil).
    line_width(lambda {|d,_p| _p.link_value * 1.5 }).
    stroke_style("rgba(0,0,0,.2)")
  l.extend LinkAdd
  l.that=self
  l
end

#_node ⇒ Object

The node prototype. This prototype is intended to be used with a Dot mark in conjunction with the link prototype.



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# File 'lib/rubyvis/layout/network.rb', line 89

def _node
  that=self        
  m=Mark.new().
    data(lambda {that.nodes}).
    stroke_style("#1f77b4").
    fill_style("#fff").
    left(lambda {|n| n.x }).
    top(lambda {|n| n.y })
  m.parent = self
  m 
end

#_node_label ⇒ Object

The node label prototype, which renders the node name adjacent to the node. This prototype is provided as an alternative to using the anchor on the node mark; it is primarily intended to be used with radial node-link layouts, since it provides a convenient mechanism to set the text angle.

NOTE FOR PROTOVIS USERS: The original name of method was label but it was replaced to not conflict with Mark.label()



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# File 'lib/rubyvis/layout/network.rb', line 135

def _node_label
  that=self
  nl=Mark.new().
    mark_extend(@node).
    text_margin(7).
    text_baseline("middle").
    text(lambda {|n| n.node_name ? n.node_name : n.node_value }).
    text_angle(lambda {|n| 
      a = n.mid_angle
      Rubyvis::Wedge.upright(a) ? a : (a + Math::PI)
    }).
    text_align(lambda {|n| 
      Rubyvis::Wedge.upright(n.mid_angle) ? "left" : "right"
    })
  nl.parent = self
  nl
end

#build_implied(s) ⇒ Object 



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# File 'lib/rubyvis/layout/network.rb', line 200

def build_implied(s)        
  network_build_implied(s)
end

#build_properties(s, properties) ⇒ Object 



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# File 'lib/rubyvis/layout/network.rb', line 192

def build_properties(s, properties)
  s_id=s._id
  s_id||=0
  if (s_id < self._id)
    layout_build_properties(s,properties)
  end
end

#network_build_implied(s) ⇒ Object 



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# File 'lib/rubyvis/layout/network.rb', line 203

def network_build_implied(s)
  layout_build_implied(s)
  return true if (!s._id.nil? and s._id >= self._id)
  s._id= self._id
  
  s.nodes.each do |d|
    d.link_degree=0
  end
  
  s.links.each do |d|
    v=d.link_value
    if !d.source_node
      d.source_node=s.nodes[d.source]
    end
    d.source_node.link_degree+=v
    if !d.target_node
      d.target_node=s.nodes[d.target]
    end
    d.target_node.link_degree+=v
    
  end
  false
end

#nodes ⇒ Object

:class: Node Represents a node in a network layout. There is no explicit constructor; this class merely serves to document the attributes that are used on nodes in network layouts. (Note that hierarchical nodes place additional requirements on node representation, vis Rubyvis::Dom::Node



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# File 'lib/rubyvis/layout/network.rb', line 159

attr_accessor_dsl [:nodes, lambda {|v|
  out=[]
  v.each_with_index {|d,i|
    d=OpenStruct.new({:node_value=>d}) unless d.respond_to? :node_value
    d.index=i
    out.push(d)
  }
  out
}]

#reset ⇒ Object

Resets the cache, such that changes to layout property definitions will be visible on subsequent render. Unlike normal marks (and normal layouts), properties associated with network layouts are not automatically re-evaluated on render; the properties are cached, and any expensive layout algorithms are only run after the layout is explicitly reset.

(@returns Rubyvis::Layout::Network) self



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# File 'lib/rubyvis/layout/network.rb', line 185

def reset
  self._id=Rubyvis.id()
  self
end