34 lines
967 B
Mathematica
34 lines
967 B
Mathematica
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function data = twospirals(N, degrees, start, noise)
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% Generate "two spirals" dataset with N instances.
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% degrees controls the length of the spirals
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% start determines how far from the origin the spirals start, in degrees
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% noise displaces the instances from the spiral.
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% 0 is no noise, at 1 the spirals will start overlapping
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if nargin < 1
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N = 2000;
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end
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if nargin < 2
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degrees = 570;
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end
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if nargin < 3
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start = 90;
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end
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if nargin < 5
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noise = 0.2;
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end
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deg2rad = (2*pi)/360;
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start = start * deg2rad;
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N1 = floor(N/2);
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N2 = N-N1;
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n = start + sqrt(rand(N1,1)) * degrees * deg2rad;
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d1 = [-cos(n).*n + rand(N1,1)*noise sin(n).*n+rand(N1,1)*noise zeros(N1,1)];
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n = start + sqrt(rand(N1,1)) * degrees * deg2rad;
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d2 = [cos(n).*n+rand(N2,1)*noise -sin(n).*n+rand(N2,1)*noise ones(N2,1)];
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data = [d1/2;d2/2];
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end
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