IRB session using the kdtree gem

irb_session.rb

>> require 'kdtree'
true
>> point_array = [ [3,5],[14,0],[0,3],[-5,6],[-2,-3],[-4,-7],[2,-5],[0,0] ]
[
    [0] [
        [0] 3,
        [1] 5
    ],
    [1] [
        [0] 14,
        [1] 0
    ],
    [2] [
        [0] 0,
        [1] 3
    ],
    [3] [
        [0] -5,
        [1] 6
    ],
    [4] [
        [0] -2,
        [1] -3
    ],
    [5] [
        [0] -4,
        [1] -7
    ],
    [6] [
        [0] 2,
        [1] -5
    ],
    [7] [
        [0] 0,
        [1] 0
    ]
]
>> point_array.each_with_index{|e,i| e << i}
[
    [0] [
        [0] 3,
        [1] 5,
        [2] 0
    ],
    [1] [
        [0] 14,
        [1] 0,
        [2] 1
    ],
    [2] [
        [0] 0,
        [1] 3,
        [2] 2
    ],
    [3] [
        [0] -5,
        [1] 6,
        [2] 3
    ],
    [4] [
        [0] -2,
        [1] -3,
        [2] 4
    ],
    [5] [
        [0] -4,
        [1] -7,
        [2] 5
    ],
    [6] [
        [0] 2,
        [1] -5,
        [2] 6
    ],
    [7] [
        [0] 0,
        [1] 0,
        [2] 7
    ]
]
>> point_array.inject(points){ |array, element| array << element; array}
[
    [0] [
        [0] 3,
        [1] 5,
        [2] 0
    ],
    [1] [
        [0] 14,
        [1] 0,
        [2] 1
    ],
    [2] [
        [0] 0,
        [1] 3,
        [2] 2
    ],
    [3] [
        [0] -5,
        [1] 6,
        [2] 3
    ],
    [4] [
        [0] -2,
        [1] -3,
        [2] 4
    ],
    [5] [
        [0] -4,
        [1] -7,
        [2] 5
    ],
    [6] [
        [0] 2,
        [1] -5,
        [2] 6
    ],
    [7] [
        [0] 0,
        [1] 0,
        [2] 7
    ]
]
>> kd = Kdtree.new(point_array)
#<Kdtree:0x007ff443d21e48>
>> p kd.nearest(-2,-3)
4
4
>> p kd.nearestk(-2,-3,5)
[4, 7, 6, 5, 2]
[
    [0] 4,
    [1] 7,
    [2] 6,
    [3] 5,
    [4] 2
]
>> kd.nearestk(-2,-3,5).each{|index| p point_array[index] }
[-2, -3, 4]
[0, 0, 7]
[2, -5, 6]
[-4, -7, 5]
[0, 3, 2]
[
    [0] 4,
    [1] 7,
    [2] 6,
    [3] 5,
    [4] 2
]