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.


22
23
24
25
26
27
# 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

#mObject

Returns the value of attribute m


10
11
12
# File 'lib/geo_ruby/simple_features/point.rb', line 10

def m
  @m
end

#rObject (readonly)


11
12
13
# File 'lib/geo_ruby/simple_features/point.rb', line 11

def r
  @r
end

#tObject (readonly) Also known as: tet, tetha

radium and theta


11
12
13
# File 'lib/geo_ruby/simple_features/point.rb', line 11

def t
  @t
end

#xObject Also known as: lon, lng

Returns the value of attribute x


10
11
12
# File 'lib/geo_ruby/simple_features/point.rb', line 10

def x
  @x
end

#yObject Also known as: lat

Returns the value of attribute y


10
11
12
# File 'lib/geo_ruby/simple_features/point.rb', line 10

def y
  @y
end

#zObject

Returns the value of attribute z


10
11
12
# 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


373
374
375
376
377
378
379
380
381
382
383
# 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


422
423
424
425
426
427
428
429
430
431
432
# 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)


413
414
415
416
417
418
419
# 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


386
387
388
389
# 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


398
399
400
401
402
# 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


392
393
394
395
# 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


405
406
407
408
409
# 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

#[email protected]Object

Invert signal of all coordinates


350
351
352
# File 'lib/geo_ruby/simple_features/point.rb', line 350

def [email protected]
  set_x_y_z(-@x, -@y, -@z)
end

#==(other) ⇒ Object

Tests the equality of the position of points + m


199
200
201
202
# 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


345
346
347
# 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


297
298
299
# 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″


310
311
312
# 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″


303
304
305
# File 'lib/geo_ruby/simple_features/point.rb', line 303

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

#as_polarObject

Outputs an array containing polar distance and theta


340
341
342
# 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…)


170
171
172
173
174
175
176
177
178
179
180
181
182
183
# 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.


162
163
164
165
166
167
# 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_typeObject

WKB geometry type of a point


214
215
216
# 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.


206
207
208
209
210
211
# 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_boxObject

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


186
187
188
189
190
191
192
# 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.


82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
# 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.


52
53
54
# 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


245
246
247
248
249
250
# 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


232
233
234
235
236
# 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


239
240
241
242
# 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


267
268
269
270
271
272
273
# 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


277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
# 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)


258
259
260
261
262
263
264
265
# 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_rangeObject


194
195
196
# 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


138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
# 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

#radObject

radium and theta


18
19
20
# 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


40
41
42
43
44
# 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.


31
32
33
34
35
36
# 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)


61
62
63
64
65
66
67
68
69
# 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_typeObject

WKT geometry type of a point


227
228
229
# 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


219
220
221
222
223
224
# 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_degObject

Outputs theta in degrees


335
336
337
# File 'lib/geo_ruby/simple_features/point.rb', line 335

def theta_deg
  theta_rad / DEG2RAD
end

#theta_radObject

Outputs theta


325
326
327
328
329
330
331
332
# 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_coordinatesObject

Helper to get all coordinates as array.


355
356
357
358
359
360
# 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_xyObject

Simple helper for 2D maps


363
364
365
# File 'lib/geo_ruby/simple_features/point.rb', line 363

def to_xy
  [x, y]
end

#to_xyzObject

Simple helper for 3D maps


368
369
370
# File 'lib/geo_ruby/simple_features/point.rb', line 368

def to_xyz
  [x, y, z]
end