Class: ColumnPack::BinPacker

Inherits:
Object
  • Object
show all
Defined in:
lib/column_pack/bin_packer.rb

Overview

Arranges elements into bins using a simple one dimensional bin packing algorithm.

Instance Method Summary collapse

Constructor Details

#initialize(total_bins, options = {}) ⇒ BinPacker

Uses a fixed number of bins (total_bins).

Options: :algorithm specify a different bin packing algorithm (default :best_fit_decreasing)

available algorithms are :best_fit_decreasing, :best_fit_increasing

:shuffle_in_col after packing columns, shuffle the elements in each column (defaults to true)

Raises:

  • (ArgumentError) 


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# File 'lib/column_pack/bin_packer.rb', line 14

def initialize(total_bins, options = {})
  raise ArgumentError.new("Must choose a number of bins greater than zero") if total_bins <= 0

  @total_bins = total_bins
  @algorithm  = options[:algorithm] || :best_fit_decreasing

  if options.has_key? :shuffle_in_col
    @shuffle_in_col = options[:shuffle_in_col]
  else
    @shuffle_in_col = true
  end

  @elements       = []
  @needs_packing  = true
end

Instance Method Details

#add(size, content) ⇒ Object

Adds element to be packed.

Raises:

  • (ArgumentError) 


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# File 'lib/column_pack/bin_packer.rb', line 31

def add(size, content)
  raise ArgumentError.new("Bin size must be greater than zero") if size <= 0

  @elements << {:size => size.to_i, :content => content}
  @needs_packing = true
end

#bins ⇒ Object

Returns a packed multi-dimensional array of elements.



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# File 'lib/column_pack/bin_packer.rb', line 39

def bins
  pack_all if @needs_packing
  @bins
end

#empty_space ⇒ Object

Total empty space left over by uneven packing.



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# File 'lib/column_pack/bin_packer.rb', line 45

def empty_space
  pack_all if @needs_packing
  max = @sizes.each.max
  space = 0

  @sizes.each { |size| space += max - size }

  space
end