Class: Rubyvis::Layout::Pack

Inherits:
Hierarchy show all
Defined in:
lib/rubyvis/layout/pack.rb

Overview

Implements a hierarchical layout using circle-packing. The meaning of the exported mark prototypes changes slightly in the space-filling implementation:<ul>

<li>node - for rendering nodes; typically a Rubyvis::Dot.

<p><li>link - unsupported; undefined. Links are encoded implicitly in the arrangement of the space-filling nodes.

<p><li>label - for rendering node labels; typically a Rubyvis::Label.

</ul>The pack layout support dynamic sizing for leaf nodes, if a #size psuedo-property is specified. The default size function returns 1, causing all leaf nodes to be sized equally, and all internal nodes to be sized by the number of leaf nodes they have as descendants.

<p>The size function can be used in conjunction with the order property, which allows the nodes to the sorted by the computed size. Note: for sorting based on other data attributes, simply use the default null for the order property, and sort the nodes beforehand using the pv.Dom operator.

<p>For more details on how to use this layout, see Rubyvis::Layout::Hierarchy.

>“Visualization of large hierarchical data by circle packing”</a> by W. Wang,

  1. Wang, G. Dai, and H. Wang, ACM CHI 2006.

/

See Also:

  • href="http://portal.acm.org/citation.cfm?id=1124772.1124851"

Instance Attribute Summary

Attributes inherited from Network

#_id, #link, #node, #node_label

Attributes inherited from Panel

#_canvas, #children, #root

Attributes inherited from Mark

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

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Hierarchy

#hierarchy_build_implied, #links

Methods inherited from Network

#_link, #_node, #_node_label, #build_properties, #network_build_implied, #nodes, #reset

Methods inherited from Rubyvis::Layout

Arc, Cluster, Grid, Hierarchy, Horizon, Indent, Matrix, Network, Pack, Partition, Stack, Tree, Treemap, attr_accessor_dsl, #build_properties, #layout_build_implied, #layout_build_properties

Methods inherited from Panel

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

Methods inherited from Bar

#type, #width

Methods inherited from Mark

#add, #anchor, #area, attr_accessor_dsl, #bar, #bind, #build, #build_instance, #build_properties, #context, #context_apply, #context_clear, #cousin, #delete_index, #dot, #event, #execute, #first, #image, index, #index, index=, #index=, #index_defined?, #instance, #instances, #label, #last, #layout_arc, #layout_cluster, #layout_grid, #layout_horizon, #layout_indent, #layout_matrix, #layout_pack, #layout_partition, #layout_partition_fill, #layout_stack, #layout_tree, #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 ⇒ Pack

Returns a new instance of Pack.



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# File 'lib/rubyvis/layout/pack.rb', line 41

def initialize
  super
  @node.
  shape_radius(lambda {|n| n.radius }).
  stroke_style("rgb(31, 119, 180)").
  fill_style("rgba(31, 119, 180, 0.25)")


  @node_label.text_align("center")

  @link=nil

  @radius = lambda { 1 }
end

Class Method Details

.defaults ⇒ Object

Default properties for circle-packing layouts. The default spacing parameter is 1 and the default order is “ascending”.



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# File 'lib/rubyvis/layout/pack.rb', line 84

def self.defaults
  Rubyvis::Layout::Pack.new.mark_extend(Rubyvis::Layout::Hierarchy.defaults).
  spacing(1).
  order("ascending")
end

Instance Method Details

#bound(n) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 154

def bound(n)
  @x_min = [n.x - n.radius, @x_min].min
  @x_max = [n.x + n.radius, @x_max].max
  @y_min = [n.y - n.radius, @y_min].min
  @y_max = [n.y + n.radius, @y_max].max
end

#build_implied(s) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 313

def build_implied(s)
  return nil if hierarchy_build_implied(s)
  @s=s
  nodes = s.nodes
  root = nodes[0]
  radii(nodes)

  # Recursively compute the layout. #/
  root.x = 0
  root.y = 0
  root.radius = pack_tree(root)

  w = self.width
  h = self.height
  k = 1.0 / [2.0 * root.radius / w, 2.0 * root.radius / h].max
  transform(root, w / 2.0, h / 2.0, k)
end

#insert(a, b) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 160

def insert(a,b)
  c = a.n
  a.n = b
  b._p = a
  b.n = c
  c._p = b
end

#intersects(a, b) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 171

def intersects(a, b)
  dx = b.x - a.x
  dy = b.y - a.y
  dr = a.radius + b.radius
  (dr * dr - dx * dx - dy * dy) > 0.001 # within epsilon
end

#pack_circle(nodes) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 211

def pack_circle(nodes)
  @x_min = Infinity
  @x_max = -Infinity
  @y_min = Infinity
  @y_max = -Infinity
  a=b=c=j=k=nil


  # Create first node.
  a = nodes[0];
  a.x = -a.radius
  a.y = 0
  bound(a)

  # Create second node. #/
  if (nodes.size > 1)
    b = nodes[1]
    b.x = b.radius
    b.y = 0
    bound(b)

    # Create third node and build chain.
    if (nodes.size > 2)
      c = nodes[2]
      place(a, b, c)
      bound(c)
      insert(a, c)
      a._p = c
      insert(c, b)
      b = a.n

      # Now iterate through the rest.
      i=3
      while(i < nodes.size) do
        c=nodes[i]
        place(a, b, c)

        # Search for the closest intersection. #/
        isect = 0
        s1 = 1
        s2 = 1

        j=b.n
        while(j!=b) do
          if (intersects(j, c))
            isect=1
            break
          end
          j=j.n
          s1+=1
        end

        if isect==1
          k=a._p
          while(k!=j._p) do
            if(intersects(k,c))
              if(s2 < s1)
                isect=-1
                j=k
              end
              break
            end
            k=k._p
            s2+=1
          end
        end


        # Update node chain. #/
        if (isect == 0)
          insert(a, c)
          b = c
          bound(c)
        elsif (isect > 0)
          splice(a, j)
          b = j
          i-=1
        elsif (isect < 0)
          splice(j, b)
          a = j
          i-=1
        end
        i+=1
      end


    end
  end

  # Re-center the circles and return the encompassing radius. #/
  cx = (@x_min + @x_max) / 2.0
  cy = (@y_min + @y_max) / 2.0
  cr = 0
  nodes.each do |n|
    n.x -= cx
    n.y -= cy
    cr = [cr, n.radius + Math.sqrt(n.x * n.x + n.y * n.y)].max
  end
  cr + @s.spacing
end

#pack_tree(n) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 132

def pack_tree(n)
  nodes = []
  c=n.first_child
  while(c)
    c.radius=pack_tree(c) if c.first_child
    c.n=c._p=c
    nodes.push(c)
    c=c.next_sibling
  end

  # Sort.
  case @s.order
  when "ascending"
    nodes.sort {|a,b| a.radius<=>b.radius}
  when 'descending'
    nodes.sort {|a,b| b.radius<=>a.radius}
  when 'reverse'
    nodes.reverse
  end

  return pack_circle(nodes)
end

#place(a, b, c) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 179

def place(a, b, c)
  da = b.radius + c.radius
  db = a.radius + c.radius
  dx = b.x - a.x
  dy = b.y - a.y
  dc = Math.sqrt(dx * dx + dy * dy)
  cos = (db * db + dc * dc - da * da) / (2.0 * db * dc)
  theta = Math.acos(cos)
  x = cos * db
  h = Math.sin(theta) * db
  dx = dx/dc
  dy = dy/dc
  c.x = a.x + x * dx + h * dy
  c.y = a.y + x * dy - h * dx
end

#radii(nodes) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 121

def radii(nodes)
  stack=Mark.stack
  stack.unshift(nil)
  nodes.each {|c|
    if !c.first_child
      stack[0]=c
      c.radius = @radius.js_apply(self, stack)
    end
  }
  stack.shift
end

#size(f) ⇒ Object

Specifies the sizing function. By default, a sizing function is disabled and all nodes are given constant size. The sizing function is invoked for each leaf node in the tree (passed to the constructor).

<p>For example, if the tree data structure represents a file system, with files as leaf nodes, and each file has a bytes attribute, you can specify a size function as:

<pre> .size(function(d) d.bytes)</pre>

As with other properties, a size function may specify additional arguments to access the data associated with the layout and any enclosing panels.

Parameters:

  • f (function) —

    the new sizing function.



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# File 'lib/rubyvis/layout/pack.rb', line 110

def size(f)
  if f.is_a? Proc
    @radius=lambda {|*args| Math.sqrt(f.js_apply(self,args))}
  else
    f=Math.sqrt(f)
    @radius=lambda {f}
  end
  self
end

#splice(a, b) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 167

def splice(a, b)
  a.n = b
  b._p = a
end

#transform(n, x, y, k) ⇒ Object 



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# File 'lib/rubyvis/layout/pack.rb', line 196

def transform(n, x, y, k)
  c=n.first_child
  while(c) do
    c.x += n.x
    c.y += n.y
    transform(c, x, y, k)
    c=c.next_sibling
  end
  n.x = x + k * n.x
  n.y = y + k * n.y
  n.radius *= k
  n.mid_angle=0 # Undefined on protovis
end