archimedean.rb

require 'json'

def get_lonlat_in_spiral(i)
  v = Complex.polar i, i/4.9 * Math::PI/2
  angle = v.angle
  magnitude = v.magnitude
  [magnitude * Math.cos(angle), magnitude * Math.sin(angle)]
end

r = 10.upto(30).map { |i| get_lonlat_in_spiral(i) }

coords = r.map {|x, y| [139.6 + y * 0.01, 35.7 + x * 0.01] }

puts JSON.generate(
  type: "MultiPolygon",
  coordinates: [coords.map {|y, x| [y.floor(5), x.floor(5)] }.map { |y, x|
    [
      [y, x],
      [y, x + 0.01],
      [y - 0.01, x + 0.01],
      [y - 0.01, x],
      [y, x]
    ]
  }]
)

result.geojson

{
  "type": "MultiPolygon",
  "coordinates": [
    [
      [
        [
          139.59359,
          35.6002
        ],
        [
          139.59359,
          35.6102
        ],
        [
          139.58359000000002,
          35.6102
        ],
        [
          139.58359000000002,
          35.6002
        ],
        [
          139.59359,
          35.6002
        ]
      ],
      [
        [
          139.55872,
          35.59803
        ],
        [
          139.55872,
          35.60803
        ],
        [
          139.54872,
          35.60803
        ],
        [
          139.54872,
          35.59803
        ],
        [
          139.55872,
          35.59803
        ]
      ],
      [
        [
          139.52221,
          35.60862
        ],
        [
          139.52221,
          35.61862
        ],
        [
          139.51221,
          35.61862
        ],
        [
          139.51221,
          35.60862
        ],
        [
          139.52221,
          35.60862
        ]
      ],
      [
        [
          139.48883,
          35.6326
        ],
        [
          139.48883,
          35.642599999999995
        ],
        [
          139.47883000000002,
          35.642599999999995
        ],
        [
          139.47883000000002,
          35.6326
        ],
        [
          139.48883,
          35.6326
        ]
      ],
      [
        [
          139.46351,
          35.66884
        ],
        [
          139.46351,
          35.67884
        ],
        [
          139.45351000000002,
          35.67884
        ],
        [
          139.45351000000002,
          35.66884
        ],
        [
          139.46351,
          35.66884
        ]
      ],
      [
        [
          139.45069,
          35.7144
        ],
        [
          139.45069,
          35.724399999999996
        ],
        [
          139.44069000000002,
          35.724399999999996
        ],
        [
          139.44069000000002,
          35.7144
        ],
        [
          139.45069,
          35.7144
        ]
      ],
      [
        [
          139.45369,
          35.76476
        ],
        [
          139.45369,
          35.77476
        ],
        [
          139.44369,
          35.77476
        ],
        [
          139.44369,
          35.76476
        ],
        [
          139.45369,
          35.76476
        ]
      ],
      [
        [
          139.47415,
          35.81429
        ],
        [
          139.47415,
          35.82429
        ],
        [
          139.46415000000002,
          35.82429
        ],
        [
          139.46415000000002,
          35.81429
        ],
        [
          139.47415,
          35.81429
        ]
      ],
      [
        [
          139.51167,
          35.85683
        ],
        [
          139.51167,
          35.86683
        ],
        [
          139.50167000000002,
          35.86683
        ],
        [
          139.50167000000002,
          35.85683
        ],
        [
          139.51167,
          35.85683
        ]
      ],
      [
        [
          139.56367,
          35.88649
        ],
        [
          139.56367,
          35.89649
        ],
        [
          139.55367,
          35.89649
        ],
        [
          139.55367,
          35.88649
        ],
        [
          139.56367,
          35.88649
        ]
      ],
      [
        [
          139.62557,
          35.89835
        ],
        [
          139.62557,
          35.90835
        ],
        [
          139.61557000000002,
          35.90835
        ],
        [
          139.61557000000002,
          35.89835
        ],
        [
          139.62557,
          35.89835
        ]
      ],
      [
        [
          139.69111,
          35.8892
        ],
        [
          139.69111,
          35.8992
        ],
        [
          139.68111000000002,
          35.8992
        ],
        [
          139.68111000000002,
          35.8892
        ],
        [
          139.69111,
          35.8892
        ]
      ],
      [
        [
          139.75305,
          35.85803
        ],
        [
          139.75305,
          35.86803
        ],
        [
          139.74305,
          35.86803
        ],
        [
          139.74305,
          35.85803
        ],
        [
          139.75305,
          35.85803
        ]
      ],
      [
        [
          139.80391,
          35.80638
        ],
        [
          139.80391,
          35.816379999999995
        ],
        [
          139.79391,
          35.816379999999995
        ],
        [
          139.79391,
          35.80638
        ],
        [
          139.80391,
          35.80638
        ]
      ],
      [
        [
          139.83692,
          35.7383
        ],
        [
          139.83692,
          35.7483
        ],
        [
          139.82692,
          35.7483
        ],
        [
          139.82692,
          35.7383
        ],
        [
          139.83692,
          35.7383
        ]
      ],
      [
        [
          139.84679,
          35.6601
        ],
        [
          139.84679,
          35.6701
        ],
        [
          139.83679,
          35.6701
        ],
        [
          139.83679,
          35.6601
        ],
        [
          139.84679,
          35.6601
        ]
      ],
      [
        [
          139.83051,
          35.57974
        ],
        [
          139.83051,
          35.58974
        ],
        [
          139.82051,
          35.58974
        ],
        [
          139.82051,
          35.57974
        ],
        [
          139.83051,
          35.57974
        ]
      ],
      [
        [
          139.78783,
          35.50604
        ],
        [
          139.78783,
          35.51604
        ],
        [
          139.77783000000002,
          35.51604
        ],
        [
          139.77783000000002,
          35.50604
        ],
        [
          139.78783,
          35.50604
        ]
      ],
      [
        [
          139.72148,
          35.44772
        ],
        [
          139.72148,
          35.457719999999995
        ],
        [
          139.71148000000002,
          35.457719999999995
        ],
        [
          139.71148000000002,
          35.44772
        ],
        [
          139.72148,
          35.44772
        ]
      ],
      [
        [
          139.63708,
          35.41238
        ],
        [
          139.63708,
          35.42238
        ],
        [
          139.62708,
          35.42238
        ],
        [
          139.62708,
          35.41238
        ],
        [
          139.63708,
          35.41238
        ]
      ],
      [
        [
          139.54265,
          35.40553
        ],
        [
          139.54265,
          35.41553
        ],
        [
          139.53265000000002,
          35.41553
        ],
        [
          139.53265000000002,
          35.40553
        ],
        [
          139.54265,
          35.40553
        ]
      ]
    ]
  ]
}