Last change
on this file since 177 was
37,
checked in by (none), 15 years ago
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Added original make3d
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Property svn:executable set to
*
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File size:
1.2 KB
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[37] | 1 | function x = sample(p, n) |
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| 2 | %SAMPLE Sample from categorical distribution. |
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| 3 | % X = SAMPLE(P,N) returns a row vector of N integers, sampled according to the |
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| 4 | % probability distribution P (an array of numbers >= 0, whose sum is > 0). |
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| 5 | % sum(P) does not have to be 1, but it must be > 0. |
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| 6 | % X(i) ranges 1 to length(P). |
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| 7 | |
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| 8 | % Written by Tom Minka |
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| 9 | % (c) Microsoft Corporation. All rights reserved. |
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| 10 | |
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| 11 | % Written by Min Sun July 25th |
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| 12 | % adapt case when p contain Inf entries |
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| 13 | |
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| 14 | if nargin < 2 |
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| 15 | n = 1; |
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| 16 | end |
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| 17 | |
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| 18 | % process case for Inf entries in p ============== |
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| 19 | DetX = find(p == Inf); |
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| 20 | RandList = find(p ~= Inf); |
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| 21 | RandList = RandList(:); |
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| 22 | p = p( RandList); |
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| 23 | % ================================================ |
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| 24 | |
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| 25 | if n < 10 |
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| 26 | cdf = cumsum(p(:)); |
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| 27 | if cdf(end) <= 0 |
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| 28 | error('distribution is all zeros'); |
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| 29 | end |
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| 30 | RandX = zeros(1,n); |
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| 31 | for i = 1:n |
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| 32 | RandX(i) = sum(cdf < rand*cdf(end)) + 1; |
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| 33 | end |
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| 34 | else |
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| 35 | % large n method |
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| 36 | p = p(:); |
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| 37 | p = p/sum(p); |
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| 38 | h = sample_hist(p,n); |
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| 39 | RandX = zeros(1,n); |
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| 40 | i = [0 cumsum(h)']; |
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| 41 | % set RandX = [1 1 1 1 2 2 3 3 3 ... ] |
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| 42 | for k = 1:length(h) |
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| 43 | RandX((i(k)+1):i(k+1)) = k; |
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| 44 | end |
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| 45 | RandX = RandX(randperm(n)); |
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| 46 | end |
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| 47 | |
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| 48 | % ================ |
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| 49 | x = [DetX(:); RandList(RandX)]; |
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| 50 | % ================ |
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