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.

Constant Summary collapse

DEG2RAD = 
0.0174532925199433
HALFPI = 
1.5707963267948966

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_geojson, from_georss, from_georss_with_tags, from_hex_ewkb, from_kml, #to_json

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 22

def initialize(srid = DEFAULT_SRID, with_z = false, with_m = false)
  super(srid, with_z, with_m)
  @x = @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 10

def m
  @m
end

#r ⇒ Object (readonly)

Polar stuff

www.engineeringtoolbox.com/converting-cartesian-polar-coordinates-d_1347.html rcoordinate.rubyforge.org/svn/point.rb outputs radium



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# File 'lib/geo_ruby/simple_features/point.rb', line 11

def r
  @r
end

#t ⇒ Object (readonly) Also known as: tet, tetha

radium and theta



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# File 'lib/geo_ruby/simple_features/point.rb', line 11

def t
  @t
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 10

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 10

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 10

def z
  @z
end

Class Method Details

.from_coordinates(coords, srid = DEFAULT_SRID, z = false, m = false) ⇒ Object

Creates a point from an array of coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 373

def self.from_coordinates(coords, srid = DEFAULT_SRID, z = false, m = false)
  if !(z || m)
    from_x_y(coords[0], coords[1], srid)
  elsif z && m
    from_x_y_z_m(coords[0], coords[1], coords[2], coords[3], srid)
  elsif 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_latlong(lat, lon, srid = DEFAULT_SRID) ⇒ Object

Creates a point using coordinates like 22`34 23.45N



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# File 'lib/geo_ruby/simple_features/point.rb', line 422

def self.from_latlong(lat, lon, srid = DEFAULT_SRID)
  p = [lat, lon].map do |l|
    sig, deg, min, sec, cen = \
    l.scan(/(-)?(\d{1,2})\D*(\d{2})\D*(\d{2})(\D*(\d{1,3}))?/).flatten
    sig = true if l =~ /W|S/
    dec = deg.to_i + (min.to_i * 60 + "#{sec}#{cen}".to_f) / 3600
    sig ? dec * -1 : dec
  end
  point = new(srid)
  point.set_x_y(p[0], p[1])
end

.from_r_t(r, t, srid = DEFAULT_SRID) ⇒ Object Also known as: from_rad_tet

Creates a point using polar coordinates r and theta(degrees)



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# File 'lib/geo_ruby/simple_features/point.rb', line 413

def self.from_r_t(r, t, srid = DEFAULT_SRID)
  t *= DEG2RAD
  x = r * Math.cos(t)
  y = r * Math.sin(t)
  point = new(srid)
  point.set_x_y(x, y)
end

.from_x_y(x, y, srid = DEFAULT_SRID) ⇒ Object Also known as: xy, from_xy, 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 386

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 398

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: xyz, from_xyz, 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 392

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 405

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

#-@ ⇒ Object

Invert signal of all coordinates



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# File 'lib/geo_ruby/simple_features/point.rb', line 350

def -@
  set_x_y_z(-@x, -@y, -@z)
end

#==(other) ⇒ Object

Tests the equality of the position of points + m



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# File 'lib/geo_ruby/simple_features/point.rb', line 199

def ==(other)
  return false unless other.is_a?(Point)
  @x == other.x && @y == other.y && @z == other.z && @m == other.m
end

#as_json(_options = {}) ⇒ Object

Outputs the point in json format



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# File 'lib/geo_ruby/simple_features/point.rb', line 345

def as_json(_options = {})
  { type: 'Point', coordinates: to_coordinates }
end

#as_lat(options = {}) ⇒ Object

Outputs the geometry coordinate in human format: 47°52′48″N



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# File 'lib/geo_ruby/simple_features/point.rb', line 297

def as_lat(options = {})
  human_representation(options, x: x).join
end

#as_latlong(options = {}) ⇒ Object Also known as: as_ll

Outputs the geometry in coordinates format: 47°52′48″, -20°06′00″



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# File 'lib/geo_ruby/simple_features/point.rb', line 310

def as_latlong(options = {})
  human_representation(options).join(', ')
end

#as_long(options = {}) ⇒ Object Also known as: as_lng

Outputs the geometry coordinate in human format: -20°06′00W″



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# File 'lib/geo_ruby/simple_features/point.rb', line 303

def as_long(options = {})
  human_representation(options, y: y).join
end

#as_polar ⇒ Object

Outputs an array containing polar distance and theta



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# File 'lib/geo_ruby/simple_features/point.rb', line 340

def as_polar
  [r, t]
end

#bearing_text(other) ⇒ Object

Bearing from a point to another as symbols. (:n, :s, :sw, :ne…)



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# File 'lib/geo_ruby/simple_features/point.rb', line 170

def bearing_text(other)
  case bearing_to(other)
  when 1..22    then :n
  when 23..66   then :ne
  when 67..112  then :e
  when 113..146 then :se
  when 147..202 then :s
  when 203..246 then :sw
  when 247..292 then :w
  when 293..336 then :nw
  when 337..360 then :n
  else nil
  end
end

#bearing_to(other) ⇒ Object

Bearing from a point to another, in degrees.



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

def bearing_to(other)
  return 0 if self == other
  a, b =  other.x - x, other.y - y
  res =  Math.acos(b / Math.sqrt(a * a + b * b)) / Math::PI * 180
  a < 0 ? 360 - res : res
end

#binary_geometry_type ⇒ Object

WKB geometry type of a point



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

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 206

def binary_representation(allow_z = true, allow_m = true) #:nodoc:
  bin_rep = [@x.to_f, @y.to_f].pack('EE')
  bin_rep += [@z.to_f].pack('E') if @with_z && allow_z # Default value so no crash
  bin_rep += [@m.to_f].pack('E') if @with_m && 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 186

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

#ellipsoidal_distance(point, a = 6_378_137.0, b = 6_356_752.3142) ⇒ 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 WGS84 ellipsoid.



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# File 'lib/geo_ruby/simple_features/point.rb', line 82

def ellipsoidal_distance(point, a = 6_378_137.0, b = 6_356_752.3142)
  f = (a - b) / a
  l = (point.lon - lon) * DEG2RAD

  u1 = Math.atan((1 - f) * Math.tan(lat * DEG2RAD))
  u2 = Math.atan((1 - f) * Math.tan(point.lat * DEG2RAD))
  sin_u1 = Math.sin(u1)
  cos_u1 = Math.cos(u1)
  sin_u2 = Math.sin(u2)
  cos_u2 = Math.cos(u2)

  lambda = l
  lambda_p = 2 * Math::PI
  iter_limit = 20

  while (lambda - lambda_p).abs > 1e-12 && --iter_limit > 0
    sin_lambda = Math.sin(lambda)
    cos_lambda = Math.cos(lambda)
    sin_sigma = \
    Math.sqrt((cos_u2 * sin_lambda) * (cos_u2 * sin_lambda) +
              (cos_u1 * sin_u2 - sin_u1 * cos_u2 * cos_lambda) *
              (cos_u1 * sin_u2 - sin_u1 * cos_u2 * cos_lambda))

    return 0 if sin_sigma == 0 # coincident points

    cos_sigma   = sin_u1 * sin_u2 + cos_u1 * cos_u2 * cos_lambda
    sigma      = Math.atan2(sin_sigma, cos_sigma)
    sin_alpha   = cos_u1 * cos_u2 * sin_lambda / sin_sigma
    cos_sq_alpha = 1 - sin_alpha * sin_alpha
    cos2_sigma_m = cos_sigma - 2 * sin_u1 * sin_u2 / cos_sq_alpha

    # equatorial line: cos_sq_alpha=0
    cos2_sigma_m = 0 if cos2_sigma_m.nan?

    c = f / 16 * cos_sq_alpha * (4 + f * (4 - 3 * cos_sq_alpha))
    lambda_p = lambda
    lambda = l + (1 - c) * f * sin_alpha * (sigma + c * sin_sigma *
      (cos2_sigma_m + c * cos_sigma * (-1 + 2 * cos2_sigma_m *
          cos2_sigma_m)))
  end

  return NaN if iter_limit == 0 # formula failed to converge

  usq = cos_sq_alpha * (a * a - b * b) / (b * b)
  a_bis = 1 + usq / 16_384 * (4096 + usq * (-768 + usq * (320 - 175 * usq)))
  b_bis = usq / 1024 * (256 + usq * (-128 + usq * (74 - 47 * usq)))
  delta_sigma = b_bis * sin_sigma * (cos2_sigma_m + b_bis / 4 *
    (cos_sigma * (-1 + 2 * cos2_sigma_m * cos2_sigma_m) - b_bis / 6 *
      cos2_sigma_m * (-3 + 4 * sin_sigma * sin_sigma) * (-3 + 4 *
        cos2_sigma_m * cos2_sigma_m)))

  b * a_bis * (sigma - delta_sigma)
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 52

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 245

def georss_gml_representation(options) #:nodoc:
  georss_ns = options[:georss_ns] || 'georss'
  gml_ns = options[:gml_ns] || 'gml'
  "<#{georss_ns}:where>\n<#{gml_ns}:Point>\n<#{gml_ns}:pos>#{y} #{x}" \
  "</#{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 232

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 239

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

#html_representation(options = {}) ⇒ Object 



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# File 'lib/geo_ruby/simple_features/point.rb', line 267

def html_representation(options = {})
  options[:coord] = true if options[:coord].nil?
  out =  '<span class=\'geo\'>'
  out += "<abbr class='latitude' title='#{x}'>#{as_lat(options)}</abbr>"
  out += "<abbr class='longitude' title='#{y}'>#{as_long(options)}</abbr>"
  out + '</span>'
end

#human_representation(options = {}, g = { x: x, y: y }) ⇒ Object

Human representation of the geom, don’t use directly, use: #as_lat, #as_long, #as_latlong



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# File 'lib/geo_ruby/simple_features/point.rb', line 277

def human_representation(options = {}, g = { x: x, y: y })
  g.map do |k, v|
    deg = v.to_i.abs
    min = (60 * (v.abs - deg)).to_i
    labs = (v * 1_000_000).abs / 1_000_000
    sec = ((((labs - labs.to_i) * 60) -
        ((labs - labs.to_i) * 60).to_i) * 100_000) * 60 / 100_000
    str = options[:full] ? '%.i°%.2i′%05.2f″' :  '%.i°%.2i′%02.0f″'
    if options[:coord]
      out = format(str, deg, min, sec)
      # Add cardinal
      out + (k == :x ? v > 0 ? 'N' : 'S' : v > 0 ? 'E' : 'W')
    else
      format(str, v.to_i, min, sec)
    end
  end
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 258

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

#m_range ⇒ Object 



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# File 'lib/geo_ruby/simple_features/point.rb', line 194

def m_range
  [@m, @m]
end

#orthogonal_distance(line, tail = nil) ⇒ Object

Orthogonal Distance Based www.allegro.cc/forums/thread/589720



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# File 'lib/geo_ruby/simple_features/point.rb', line 138

def orthogonal_distance(line, tail = nil)
  head, tail  = tail ?  [line, tail] : [line[0], line[-1]]
  a, b = @x - head.x, @y - head.y
  c, d = tail.x - head.x, tail.y - head.y

  dot = a * c + b * d
  len = c * c + d * d
  return 0.0 if len.zero?
  res = dot / len

  xx, yy = \
  if res < 0
    [head.x, head.y]
  elsif res > 1
    [tail.x, tail.y]
  else
    [head.x + res * c, head.y + res * d]
  end
  # TODO: benchmark if worth creating an instance
  # euclidian_distance(Point.from_x_y(xx, yy))
  Math.sqrt((@x - xx)**2 + (@y - yy)**2)
end

#rad ⇒ Object

radium and theta



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# File 'lib/geo_ruby/simple_features/point.rb', line 18

def r
  @r
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 40

def set_x_y(x, y)
  @x = x && !x.is_a?(Numeric) ? x.to_f : x
  @y = y && !y.is_a?(Numeric) ? y.to_f : 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 31

def set_x_y_z(x, y, z)
  @x = x && !x.is_a?(Numeric) ? x.to_f : x
  @y = y && !y.is_a?(Numeric) ? y.to_f : y
  @z = z && !z.is_a?(Numeric) ? z.to_f : z
  self
end

#spherical_distance(point, r = 6_370_997.0) ⇒ Object

Spherical distance in meters, using ‘Haversine’ formula. with a radius of 6471000m Assumes x is the lon and y the lat, in degrees. 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 61

def spherical_distance(point, r = 6_370_997.0)
  dlat = (point.lat - lat) * DEG2RAD / 2
  dlon = (point.lon - lon) * DEG2RAD / 2

  a = Math.sin(dlat)**2 + Math.cos(lat * DEG2RAD) *
      Math.cos(point.lat * DEG2RAD) * Math.sin(dlon)**2
  c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
  r * 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 227

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 219

def text_representation(allow_z = true, allow_m = true) #:nodoc:
  tex_rep = "#{@x} #{@y}"
  tex_rep += " #{@z}" if @with_z && allow_z
  tex_rep += " #{@m}" if @with_m && allow_m
  tex_rep
end

#theta_deg ⇒ Object

Outputs theta in degrees



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# File 'lib/geo_ruby/simple_features/point.rb', line 335

def theta_deg
  theta_rad / DEG2RAD
end

#theta_rad ⇒ Object

Outputs theta



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# File 'lib/geo_ruby/simple_features/point.rb', line 325

def theta_rad
  if @x.zero?
    @y < 0 ? 3 * HALFPI : HALFPI
  else
    th = Math.atan(@y / @x)
    r > 0 ? th + 2 * Math::PI : th
  end
end

#to_coordinates ⇒ Object

Helper to get all coordinates as array.



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# File 'lib/geo_ruby/simple_features/point.rb', line 355

def to_coordinates
  coord = [x, y]
  coord << z if with_z
  coord << m if with_m
  coord
end

#to_xy ⇒ Object

Simple helper for 2D maps



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# File 'lib/geo_ruby/simple_features/point.rb', line 363

def to_xy
  [x, y]
end

#to_xyz ⇒ Object

Simple helper for 3D maps



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# File 'lib/geo_ruby/simple_features/point.rb', line 368

def to_xyz
  [x, y, z]
end