Class: Geospatial::Hilbert::Curve
- Inherits:
-
Object
- Object
- Geospatial::Hilbert::Curve
- Defined in:
- lib/geospatial/hilbert/curve.rb
Instance Attribute Summary collapse
-
#dimensions ⇒ Object
readonly
Returns the value of attribute dimensions.
-
#order ⇒ Object
readonly
Returns the value of attribute order.
-
#scale ⇒ Object
readonly
Returns the value of attribute scale.
Instance Method Summary collapse
- #bit_width ⇒ Object
-
#initialize(dimensions, order = 30) ⇒ Curve
constructor
A new instance of Curve.
- #map(coordinates) ⇒ Object
- #origin ⇒ Object
- #size ⇒ Object
- #to_s ⇒ Object
-
#traverse(&block) ⇒ Object
This is a helper entry point for traversing Hilbert space.
-
#traverse_recurse(order, mask, value, origin, size, &block) ⇒ Object
Traversal enumerates all regions of a curve, top-down.
- #unmap(value) ⇒ Object
Constructor Details
#initialize(dimensions, order = 30) ⇒ Curve
Returns a new instance of Curve.
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# File 'lib/geospatial/hilbert/curve.rb', line 27 def initialize(dimensions, order = 30) raise ArgumentError("Order #{order} must be positive integer!") unless order >= 1 # Order is the number of levels of the curve, which is equivalent to the number of bits per dimension. @order = order @scale = 2**@order @dimensions = dimensions * @scale @origin = dimensions.origin @size = dimensions.size end |
Instance Attribute Details
#dimensions ⇒ Object (readonly)
Returns the value of attribute dimensions.
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# File 'lib/geospatial/hilbert/curve.rb', line 41 def dimensions @dimensions end |
#order ⇒ Object (readonly)
Returns the value of attribute order.
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# File 'lib/geospatial/hilbert/curve.rb', line 39 def order @order end |
#scale ⇒ Object (readonly)
Returns the value of attribute scale.
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# File 'lib/geospatial/hilbert/curve.rb', line 40 def scale @scale end |
Instance Method Details
#bit_width ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 62 def bit_width @dimensions.count end |
#map(coordinates) ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 92 def map(coordinates) axes = @dimensions.map(coordinates).map(&:floor) index = OrdinalIndex.new(axes, @order) return index.to_hilbert.to_i end |
#origin ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 43 def origin @dimensions.origin end |
#size ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 47 def size @dimensions.size end |
#to_s ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 51 def to_s "\#<#{self.class} order=#{@order} dimensions=#{@dimensions}>" end |
#traverse(&block) ⇒ Object
This is a helper entry point for traversing Hilbert space.
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# File 'lib/geospatial/hilbert/curve.rb', line 56 def traverse(&block) return to_enum(:traverse) unless block_given? traverse_recurse(@order-1, 0, 0, self.origin, self.size, &block) end |
#traverse_recurse(order, mask, value, origin, size, &block) ⇒ Object
Traversal enumerates all regions of a curve, top-down.
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# File 'lib/geospatial/hilbert/curve.rb', line 67 def traverse_recurse(order, mask, value, origin, size, &block) half_size = size.collect{|value| value * 0.5}.freeze prefix_mask = (1 << order) | mask (2**bit_width).times do |prefix| # These both do the same thing, not sure which one is faster: child_value = (value << @dimensions.count) | prefix prefix = child_value << (order*bit_width) index = HilbertIndex.from_integral(prefix, bit_width, @order).to_ordinal index = index & prefix_mask child_origin = @dimensions.unmap(index.axes).freeze # puts "yield(#{child_origin}, #{half_size}, #{prefix}, #{order})" # We avoid calling traverse_recurse simply to hit the callback on the leaf nodes: result = yield child_origin, half_size, prefix, order if order > 0 and result != :skip self.traverse_recurse(order - 1, prefix_mask, child_value, child_origin, half_size, &block) end end end |
#unmap(value) ⇒ Object
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# File 'lib/geospatial/hilbert/curve.rb', line 100 def unmap(value) index = HilbertIndex.from_integral(value, @dimensions.count, @order) return @dimensions.unmap(index.to_ordinal.axes) end |