Class: GeoRuby::SimpleFeatures::Point

Inherits:
Geometry
  • Object
show all
Defined in:
lib/geo_ruby/simple_features/point.rb

Overview

Represents a point. It is in 3D if the Z coordinate is not nil.

Instance Attribute Summary collapse

Attributes inherited from Geometry

#srid, #with_m, #with_z

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Geometry

#as_ewkb, #as_ewkt, #as_georss, #as_hex_ewkb, #as_hex_wkb, #as_kml, #as_wkb, #as_wkt, #envelope, from_ewkb, from_ewkt, from_georss, from_georss_with_tags, from_hex_ewkb, from_kml, kml_to_wkt

Constructor Details

#initialize(srid = DEFAULT_SRID, with_z = false, with_m = false) ⇒ Point

Returns a new instance of Point.



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# File 'lib/geo_ruby/simple_features/point.rb', line 14

def initialize(srid=DEFAULT_SRID,with_z=false,with_m=false)
  super(srid,with_z,with_m)
  @x=0.0
  @y=0.0
  @z=0.0 #default value : meaningful if with_z

  @m=0.0 #default value : meaningful if with_m

end

Instance Attribute Details

#m ⇒ Object

Returns the value of attribute m.



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# File 'lib/geo_ruby/simple_features/point.rb', line 8

def m
  @m
end

#x ⇒ Object Also known as: lon, lng

Returns the value of attribute x.



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# File 'lib/geo_ruby/simple_features/point.rb', line 8

def x
  @x
end

#y ⇒ Object Also known as: lat

Returns the value of attribute y.



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# File 'lib/geo_ruby/simple_features/point.rb', line 8

def y
  @y
end

#z ⇒ Object

Returns the value of attribute z.



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# File 'lib/geo_ruby/simple_features/point.rb', line 8

def z
  @z
end

Class Method Details

.from_coordinates(coords, srid = DEFAULT_SRID, with_z = false, with_m = false) ⇒ Object

creates a point from an array of coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 188

def self.from_coordinates(coords,srid=DEFAULT_SRID,with_z=false,with_m=false)
  if ! (with_z or with_m)
    from_x_y(coords[0],coords[1],srid)
  elsif with_z and with_m
    from_x_y_z_m(coords[0],coords[1],coords[2],coords[3],srid)
  elsif with_z
    from_x_y_z(coords[0],coords[1],coords[2],srid)
  else
    from_x_y_m(coords[0],coords[1],coords[2],srid) 
  end
end

.from_x_y(x, y, srid = DEFAULT_SRID) ⇒ Object Also known as: from_lon_lat

creates a point from the X and Y coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 201

def self.from_x_y(x,y,srid=DEFAULT_SRID)
  point= new(srid)
  point.set_x_y(x,y)
end

.from_x_y_m(x, y, m, srid = DEFAULT_SRID) ⇒ Object Also known as: from_lon_lat_m

creates a point from the X, Y and M coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 214

def self.from_x_y_m(x,y,m,srid=DEFAULT_SRID)
  point= new(srid,false,true)
  point.m=m
  point.set_x_y(x,y)
end

.from_x_y_z(x, y, z, srid = DEFAULT_SRID) ⇒ Object Also known as: from_lon_lat_z

creates a point from the X, Y and Z coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 207

def self.from_x_y_z(x,y,z,srid=DEFAULT_SRID)
  point= new(srid,true)
  point.set_x_y_z(x,y,z)
end

.from_x_y_z_m(x, y, z, m, srid = DEFAULT_SRID) ⇒ Object Also known as: from_lon_lat_z_m

creates a point from the X, Y, Z and M coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 221

def self.from_x_y_z_m(x,y,z,m,srid=DEFAULT_SRID)
  point= new(srid,true,true)
  point.m=m
  point.set_x_y_z(x,y,z)
end

Instance Method Details

#==(other_point) ⇒ Object

tests the equality of the position of points + m



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# File 'lib/geo_ruby/simple_features/point.rb', line 123

def ==(other_point)
  if other_point.class != self.class
    false
  else
    @x == other_point.x and @y == other_point.y and @z == other_point.z and @m == other_point.m
  end
end

#binary_geometry_type ⇒ Object

WKB geometry type of a point



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# File 'lib/geo_ruby/simple_features/point.rb', line 139

def binary_geometry_type#:nodoc:

  1
end

#binary_representation(allow_z = true, allow_m = true) ⇒ Object

binary representation of a point. It lacks some headers to be a valid EWKB representation.



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# File 'lib/geo_ruby/simple_features/point.rb', line 132

def binary_representation(allow_z=true,allow_m=true) #:nodoc:

  bin_rep = [@x,@y].pack("EE")
  bin_rep += [@z].pack("E") if @with_z and allow_z #Default value so no crash

  bin_rep += [@m].pack("E") if @with_m and allow_m #idem

  bin_rep
end

#bounding_box ⇒ Object

Bounding box in 2D/3D. Returns an array of 2 points



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# File 'lib/geo_ruby/simple_features/point.rb', line 110

def bounding_box
  unless with_z
    [Point.from_x_y(@x,@y),Point.from_x_y(@x,@y)]
  else
    [Point.from_x_y_z(@x,@y,@z),Point.from_x_y_z(@x,@y,@z)]
  end
end

#ellipsoidal_distance(point, a = 6378137.0, b = 6356752.3142) ⇒ Object

Ellipsoidal distance in m using Vincenty’s formula. Lifted entirely from Chris Veness’s code at www.movable-type.co.uk/scripts/LatLongVincenty.html and adapted for Ruby. Assumes the x and y are the lon and lat in degrees. a is the semi-major axis (equatorial radius) of the ellipsoid b is the semi-minor axis (polar radius) of the ellipsoid Their values by default are set to the ones of the WGS84 ellipsoid



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# File 'lib/geo_ruby/simple_features/point.rb', line 62

def ellipsoidal_distance(point, a = 6378137.0, b = 6356752.3142)
  deg_to_rad = 0.0174532925199433
  
  f = (a-b) / a
  l = (point.lon - lon) * deg_to_rad
  
  u1 = Math.atan((1-f) * Math.tan(lat * deg_to_rad ))
  u2 = Math.atan((1-f) * Math.tan(point.lat * deg_to_rad))
  sinU1 = Math.sin(u1)
  cosU1 = Math.cos(u1)
  sinU2 = Math.sin(u2)
  cosU2 = Math.cos(u2)
  
  lambda = l
  lambdaP = 2 * Math::PI
  iterLimit = 20
  
  while (lambda-lambdaP).abs > 1e-12 && --iterLimit>0
    sinLambda = Math.sin(lambda)
    cosLambda = Math.cos(lambda)
    sinSigma = Math.sqrt((cosU2*sinLambda) * (cosU2*sinLambda) + (cosU1*sinU2-sinU1*cosU2*cosLambda) * (cosU1*sinU2-sinU1*cosU2*cosLambda))
    
    return 0 if sinSigma == 0 #coincident points

    
    cosSigma = sinU1*sinU2 + cosU1*cosU2*cosLambda
    sigma = Math.atan2(sinSigma, cosSigma)
    sinAlpha = cosU1 * cosU2 * sinLambda / sinSigma
    cosSqAlpha = 1 - sinAlpha*sinAlpha
    cos2SigmaM = cosSigma - 2*sinU1*sinU2/cosSqAlpha
    
    cos2SigmaM = 0 if (cos2SigmaM.nan?) #equatorial line: cosSqAlpha=0


    c = f/16*cosSqAlpha*(4+f*(4-3*cosSqAlpha))
    lambdaP = lambda
    lambda = l + (1-c) * f * sinAlpha * (sigma + c * sinSigma * (cos2SigmaM + c * cosSigma * (-1 + 2 * cos2SigmaM * cos2SigmaM)))
  end
  return NaN if iterLimit==0 #formula failed to converge


  uSq = cosSqAlpha * (a*a - b*b) / (b*b)
  a_bis = 1 + uSq/16384*(4096+uSq*(-768+uSq*(320-175*uSq)))
  b_bis = uSq/1024 * (256+uSq*(-128+uSq*(74-47*uSq)))
  deltaSigma = b_bis * sinSigma*(cos2SigmaM + b_bis/4*(cosSigma*(-1+2*cos2SigmaM*cos2SigmaM)- b_bis/6*cos2SigmaM*(-3+4*sinSigma*sinSigma)*(-3+4*cos2SigmaM*cos2SigmaM)))

  b*a_bis*(sigma-deltaSigma)
end

#euclidian_distance(point) ⇒ Object

Return the distance between the 2D points (ie taking care only of the x and y coordinates), assuming the points are in projected coordinates. Euclidian distance in whatever unit the x and y ordinates are.



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# File 'lib/geo_ruby/simple_features/point.rb', line 39

def euclidian_distance(point)
  Math.sqrt((point.x - x)**2 + (point.y - y)**2)
end

#georss_gml_representation(options) ⇒ Object

georss gml representation



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# File 'lib/geo_ruby/simple_features/point.rb', line 167

def georss_gml_representation(options) #:nodoc:

  georss_ns = options[:georss_ns] || "georss"
  gml_ns = options[:gml_ns] || "gml"
  result = "<#{georss_ns}:where>\n<#{gml_ns}:Point>\n<#{gml_ns}:pos>"
  result += "#{y} #{x}"
  result += "</#{gml_ns}:pos>\n</#{gml_ns}:Point>\n</#{georss_ns}:where>\n"
end

#georss_simple_representation(options) ⇒ Object

georss simple representation



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# File 'lib/geo_ruby/simple_features/point.rb', line 156

def georss_simple_representation(options) #:nodoc:

  georss_ns = options[:georss_ns] || "georss"
  geom_attr = options[:geom_attr]
  "<#{georss_ns}:point#{geom_attr}>#{y} #{x}</#{georss_ns}:point>\n"
end

#georss_w3cgeo_representation(options) ⇒ Object

georss w3c representation



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# File 'lib/geo_ruby/simple_features/point.rb', line 162

def georss_w3cgeo_representation(options) #:nodoc:

  w3cgeo_ns = options[:w3cgeo_ns] || "geo"
  "<#{w3cgeo_ns}:lat>#{y}</#{w3cgeo_ns}:lat>\n<#{w3cgeo_ns}:long>#{x}</#{w3cgeo_ns}:long>\n"
end

#kml_representation(options = {}) ⇒ Object

outputs the geometry in kml format : options are :id, :tesselate, :extrude, :altitude_mode. If the altitude_mode option is not present, the Z (if present) will not be output (since it won’t be used by GE anyway: clampToGround is the default)



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# File 'lib/geo_ruby/simple_features/point.rb', line 178

def kml_representation(options = {}) #:nodoc: 

  result = "<Point#{options[:id_attr]}>\n"
  result += options[:geom_data] if options[:geom_data]
  result += "<coordinates>#{x},#{y}"
  result += ",#{options[:fixed_z] || z ||0}" if options[:allow_z]
  result += "</coordinates>\n"
  result += "</Point>\n"
end

#m_range ⇒ Object 



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# File 'lib/geo_ruby/simple_features/point.rb', line 118

def m_range
  [@m,@m]
end

#set_x_y(x, y) ⇒ Object Also known as: set_lon_lat

sets all coordinates of a 2D point in one call



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# File 'lib/geo_ruby/simple_features/point.rb', line 31

def set_x_y(x,y)
  @x=x
  @y=y
  self
end

#set_x_y_z(x, y, z) ⇒ Object Also known as: set_lon_lat_z

sets all coordinates in one call. Use the m accessor to set the m.



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# File 'lib/geo_ruby/simple_features/point.rb', line 22

def set_x_y_z(x,y,z)
  @x=x
  @y=y
  @z=z
  self
end

#spherical_distance(point, radius = 6370997.0) ⇒ Object

Returns the sperical distance in m, with a radius of 6471000m, with the haversine law. Assumes x is the lon and y the lat, in degrees (Changed in version 1.1). The user has to make sure using this distance makes sense (ie she should be in latlon coordinates)



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# File 'lib/geo_ruby/simple_features/point.rb', line 44

def spherical_distance(point,radius=6370997.0)
  deg_to_rad = 0.0174532925199433
  
  radlat_from = lat * deg_to_rad
  radlat_to = point.lat * deg_to_rad
  
  dlat = (point.lat - lat) * deg_to_rad
  dlon = (point.lon - lon) * deg_to_rad
 
  a = Math.sin(dlat/2)**2 + Math.cos(radlat_from) * Math.cos(radlat_to) * Math.sin(dlon/2)**2
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a))
  radius * c
end

#text_geometry_type ⇒ Object

WKT geometry type of a point



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# File 'lib/geo_ruby/simple_features/point.rb', line 151

def text_geometry_type #:nodoc:

  "POINT"
end

#text_representation(allow_z = true, allow_m = true) ⇒ Object

text representation of a point



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# File 'lib/geo_ruby/simple_features/point.rb', line 144

def text_representation(allow_z=true,allow_m=true) #:nodoc:

  tex_rep = "#{@x} #{@y}"
  tex_rep += " #{@z}" if @with_z and allow_z
  tex_rep += " #{@m}" if @with_m and allow_m
  tex_rep
end