Class: Terraformer::Polygon

Inherits:
Geometry show all
Defined in:
lib/terraformer/polygon.rb

Constant Summary

Constants inherited from Geometry

Geometry::MULTI_REGEX

Instance Attribute Summary

Attributes inherited from Geometry

#coordinates, #crs

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Geometry

#convex_hull, #each_coordinate, #geographic?, #get, #intersects?, iter_coordinate, #map_coordinate, #mercator?, #to_feature, #to_geographic, #to_hash, #to_mercator

Methods included from Geometry::ClassMethods

#arrays_intersect_arrays?, #coordinates_contain_point?, #edge_intersects_edge?, #line_contains_point?

Methods inherited from Primitive

#bbox, #envelope, #to_json, #type

Constructor Details

#initialize(*args) ⇒ Polygon

Returns a new instance of Polygon.



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# File 'lib/terraformer/polygon.rb', line 5

def initialize *args

  # each arg is a position of the polygon
  if Coordinate === args[0] || (Array === args[0] && Numeric === args[0][0])
    self.coordinates = [Coordinate.from_array(args)]

  elsif Array === args[0]

    # each arg is an array of positions; first is polygon, rest are "holes"
    if Coordinate === args[0][0] ||
       Array === args[0][0] && Numeric === args[0][0][0]
      self.coordinates = Coordinate.from_array args

    # arg is an array of polygon, holes
    elsif Array === args[0][0] && Array === args[0][0][0]
      self.coordinates = Coordinate.from_array *args
    end

  else
    super *args
  end

  # must be an array of arrays of coordinates
  unless Array === coordinates &&
         Array === coordinates[0] &&
         Terraformer::Coordinate === coordinates[0][0]
    raise ArgumentError.new 'invalid coordinates for Terraformer::Polygon'
  end

  if line_strings.map(&:linear_ring?).include? false
    raise ArgumentError.new 'not linear ring'
  end
end

Class Method Details

.polygonally_equal?(a, b) ⇒ Boolean

Returns:

  • (Boolean)

Raises:

  • (ArgumentError) 


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# File 'lib/terraformer/polygon.rb', line 144

def self.polygonally_equal? a, b
  if Terraformer::Coordinate === a ||
     Terraformer::Coordinate === b
    return a == b
  end

  raise ArgumentError unless Enumerable === a
  raise ArgumentError unless Enumerable === b

  # polygons must be the same length
  return false if a.length != b.length

  # polygons must have the last element be a duplicate
  # polygon-closing coordinate
  return false if a[0] != a[-1]
  return false if b[0] != b[-1]

  equal = true

  # clone so can pop/rotate
  a = a.clone
  b = b.clone

  # pop to drop the duplicate, polygon-closing, coordinate
  a.pop
  b.pop

  begin
    b.rotate_until_first_equals a[0]
    return a == b
  rescue IndexError
    return false
  end
end

Instance Method Details

#==(obj) ⇒ Object 



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# File 'lib/terraformer/polygon.rb', line 47

def == obj
  super obj do |o|

    equal = true

    # first check outer polygon
    equal = Polygon.polygonally_equal? self.coordinates[0], obj.coordinates[0]

    # then inner polygons (holes)
    #
    if equal
      if self.coordinates.length == obj.coordinates.length and obj.coordinates.length > 1

        self_holes = self.coordinates[1..-1].sort
        obj_holes = obj.coordinates[1..-1].sort

        self_holes.each_with_index do |hole, idx|
          equal = Polygon.polygonally_equal? hole, obj_holes[idx]
          break unless equal
        end
      end
    end

    equal
  end
end

#add_vertex(p) ⇒ Object Also known as: << 



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# File 'lib/terraformer/polygon.rb', line 122

def add_vertex p
  insert_vertex -2, p
end

#contains?(obj) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/terraformer/polygon.rb', line 83

def contains? obj
  obj = Coordinate.new obj if Array === obj and Numeric === obj[0]
  obj = obj.to_point if Coordinate === obj
  contained = false
  case obj
  when Point
    contained = Geometry.coordinates_contain_point? coordinates[0], obj.coordinates
    contained = !holes.any? {|h| h.contains? obj} if contained and has_holes?
  when MultiPoint
    contained = obj.points.all? {|p| contains? p}
  when LineString
    contained = contains?(obj.first_coordinate) && !Geometry.array_intersects_multi_array?(obj.coordinates, coordinates)
  when MultiLineString
    contained = obj.line_strings.all? {|ls| contains? ls}
  when Polygon
    contained = obj.within? self
  when MultiPolygon
    contained = obj.polygons.all? {|p| p.within? self}
  else
    raise ArgumentError.new "unsupported type: #{obj.type rescue obj.class}"
  end
  contained
end

#first_coordinate ⇒ Object 



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# File 'lib/terraformer/polygon.rb', line 43

def first_coordinate
  coordinates[0][0]
end

#has_holes? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/terraformer/polygon.rb', line 39

def has_holes?
  coordinates.length > 1
end

#holes ⇒ Object 



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# File 'lib/terraformer/polygon.rb', line 78

def holes
  return nil unless has_holes?
  coordinates[1..-1].map {|hole| Polygon.new hole}
end

#insert_vertex(idx, p) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/terraformer/polygon.rb', line 127

def insert_vertex idx, p
  p = p.coordinates if Point === p
  raise ArgumentError unless Coordinate === p
  coordinates[0].insert idx, p
end

#line_strings ⇒ Object 



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# File 'lib/terraformer/polygon.rb', line 74

def line_strings
  coordinates.map {|lr| LineString.new lr}
end

#remove_vertex(p) ⇒ Object

Raises:

  • (ArgumentError) 


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# File 'lib/terraformer/polygon.rb', line 133

def remove_vertex p
  p = p.coordinates if Point === p
  raise ArgumentError unless Coordinate === p
  coordinates[0].delete p
end

#remove_vertex_at(idx) ⇒ Object 



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# File 'lib/terraformer/polygon.rb', line 139

def remove_vertex_at idx
  coordinates[0].delete_at idx
end

#within?(obj) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/terraformer/polygon.rb', line 107

def within? obj
  case obj
  when Polygon
    if self == obj
      true
    elsif obj.contains? first_coordinate
      !Geometry.arrays_intersect_arrays?(coordinates, obj.coordinates)
    end
  when MultiPolygon
    obj.polygons.any? {|p| p.contains? self}
  else
    raise ArgumentError.new "unsupported type: #{obj.type rescue obj.class}"
  end
end