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comparison tvii/dataset/circle.py @ 87:9d5a5e9f5c3b

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add kmeans + dataset
author Jeff Hammel <k0scist@gmail.com>
date Sun, 17 Dec 2017 14:05:57 -0800
parents
children 596dac7f3e98
comparison
equal deleted inserted replaced
86:b56d329c238d 87:9d5a5e9f5c3b
1 #!/usr/bin/env python
2
3 """
4 random points in a circle
5 """
6 # TODO: a `D`-sphere
7
8 import math
9 import random
10 import sys
11 from .cli import DatasetGenerationParser
12
13
14 class CircularRandom(object):
15
16 twopi = 2.*math.pi
17
18 def __init__(self, center, radius=1.):
19 """
20 center -- (x,y) center of circle
21 """
22
23 assert radius > 0
24 self.center = (x, y) = center
25 self.radius = radius
26
27 def __call__(self, n_points):
28 """samples `n_points`"""
29
30 return [self.point() for _ in xrange(n_points)]
31
32 def point(self):
33 """samples a single point"""
34 # TODO: because area grows as 1/r, this will bias
35 # points towards the center. This should be corrected
36
37 r = self.radius*random.random()
38 theta = self.twopi*random.random()
39 x = math.cos(theta)
40 y = math.sqrt(1. - x*x)
41 if theta > math.pi:
42 y = -y
43 return (self.center[0] + x*r,
44 self.center[1] + y*r)
45
46
47 def main(args=sys.argv[1:]):
48 """CLI"""
49
50 # parse command line
51 parser = DatasetGenerationParser(description=__doc__)
52 parser.add_argument('--center', dest='center',
53 nargs=2, metavar=('X', 'Y'),
54 type=float, default=(0., 0.),
55 help="center of circle [DEFAULT: %(default)s]")
56 parser.add_argument('-R', '--radius', dest='radius',
57 type=float, default=1.,
58 help="radius of circle [DEFAULT: %(default)s]")
59 options = parser.parse_args(args)
60
61 # instantiate sampler
62 circle = CircularRandom(options.center, options.radius)
63
64 # get writer
65 writer = parser.writer()
66
67 # sample
68 points = circle(options.number)
69
70 # output
71 writer.writerows(points)
72
73 if __name__ == '__main__':
74 main()