Class: FpGrowth::Miner::PatternBaseExtractor

Inherits:
Object
  • Object
show all
Defined in:
lib/fpgrowth/miner/pattern_base_extractor.rb

Instance Method Summary collapse

Constructor Details

#initialize(tree = FpTree.new, item) ⇒ PatternBaseExtractor

Returns a new instance of PatternBaseExtractor.



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 8

def initialize(tree=FpTree.new, item)
  @tree = tree
  @horizontal_cursor = tree.heads[item]
  @conditional_item = item
  @patterns=[]
end

Instance Method Details

#down_to_top_traversal(current_branch = @current_branch, vertical_cursor = @vertical_cursor) ⇒ Object

Method accountable of reading the upper part of the branch

Each step, it makes a new node with the same item, but with minimum support Then the new node is added to a list Finally, the list is reversed



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 52

def down_to_top_traversal(current_branch=@current_branch, vertical_cursor=@vertical_cursor)
  @vertical_cursor = vertical_cursor
  while @vertical_cursor != nil and @vertical_cursor.item != nil
    down_to_top_traversal_step()
    @vertical_cursor = @vertical_cursor.parent
  end
  current_branch.reverse!
end

#down_to_top_traversal_step(current_branch = @current_branch, vertical_cursor = @vertical_cursor, min_support = @min_support) ⇒ Object

Method wich represent a step of the vertical down_to_top_traversal

It just gather items



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 65

def down_to_top_traversal_step(current_branch=@current_branch, vertical_cursor=@vertical_cursor, min_support=@min_support)
  current_branch << vertical_cursor.item
end

#execute ⇒ Object 



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 15

def execute()
  horizontal_traversal()
  return @patterns
end

#horizontal_traversal(horizontal_cursor = @horizontal_cursor) ⇒ Object

Method accountable of horizontal tree traversal



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 22

def horizontal_traversal(horizontal_cursor=@horizontal_cursor)
  @horizontal_cursor=horizontal_cursor
  while @horizontal_cursor != nil
    horizontal_traversal_step()
    @horizontal_cursor = @horizontal_cursor.lateral
  end
end

#horizontal_traversal_step(horizontal_cursor = @horizontal_cursor) ⇒ Object

Method accountable of treating each branch

Make a copy of the item branch and append it to tree

To achieve it, it make a list of the upper nodes Then build a Pattern



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# File 'lib/fpgrowth/miner/pattern_base_extractor.rb', line 37

def horizontal_traversal_step(horizontal_cursor=@horizontal_cursor)
  @min_support = horizontal_cursor.support
  @current_branch = []
  @vertical_cursor = horizontal_cursor.parent
  @current_branch = down_to_top_traversal()
  @patterns << Pattern.new(@current_branch, @min_support)
end