extension of symbols or probabilities
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i am having this p=[ 0.3,0.25, 0.20, 0.10, 0.05, 0.04, 0.04, .02]; these are 8 symbols suppose A,B,C,D,E,F,G,H
now i want to extend these from 8 to 64
how to do that? using these above probabilities
回答(4 个)
Walter Roberson
2013-6-2
My guess at what you want is
oldx = linspace(0,1,8);
newx = linspace(0,1,64);
newp = interp1(oldx, p, newx);
plot(oldx, p, 'b.', newx, newp, 'g')
The new entries will be linear interpolations of the old ones. You might prefer to use a non-linear interpolation.
1 个评论
Walter Roberson
2013-6-2
ndim = 3; %8 to the how many?
[t{1:ndim}] = ndgrid(p);
newp = prod(cat(ndim+1, t{:}), ndim+1);
The answers are now in the n-dimensional matrix newp; e.g., BDH is newp(2,4,8)
Azzi Abdelmalek
2013-6-2
编辑:Azzi Abdelmalek
2013-6-2
s='A':'H'
p=[ 0.3,0.25, 0.20, 0.10, 0.05, 0.04, 0.04, .02]
idx=arrangement(1:8,2)
new_s=s(idx)
new_p=prod(p(idx),2)
out=[cellstr(new_s) num2cell(new_p)]
%-----------------------------------------------------------------
function y=arrangement(v,n)
m=length(v);
y=zeros(m^n,n);
for k = 1:n
y(:,k) = repmat(reshape(repmat(v,m^(n-k),1),m*m^(n-k),1),m^(k-1),1);
end
5 个评论
Walter Roberson
2013-6-3
The A[sub n][super k] given in that article is the same as the P(n,k) in Permutations, and your formula looks to me like the probability mass function of the Multinomial Distribution
I haven't worked through to see if your formula is correct. Even if it is, I would think that the version I gave in my answer (starting with "ndim = 3" is a lot easier to understand. Yours might require a factor of ndim less memory, though.
Image Analyst
2013-6-2
My guess at what he wants:
probabilityTable = p' * p
probabilityTable =
0.09 0.075 0.06 0.03 0.015 0.012 0.012 0.006
0.075 0.0625 0.05 0.025 0.0125 0.01 0.01 0.005
0.06 0.05 0.04 0.02 0.01 0.008 0.008 0.004
0.03 0.025 0.02 0.01 0.005 0.004 0.004 0.002
0.015 0.0125 0.01 0.005 0.0025 0.002 0.002 0.001
0.012 0.01 0.008 0.004 0.002 0.0016 0.0016 0.0008
0.012 0.01 0.008 0.004 0.002 0.0016 0.0016 0.0008
0.006 0.005 0.004 0.002 0.001 0.0008 0.0008 0.0004
It's a 2D table of the probability of that pair, so you just enter in the two letters as indexes. For example, probabilityTable(1,1) = 0.03 * 0.03 = 0.009 just like he wanted. Of course you could convert to a 1D table if you wanted:
probabilityTable = probabilityTable(:);
2 个评论
Image Analyst
2013-6-3
You're right. I didn't notice at first because I saw the reshape(). I actually think it's more convenient to use the 2D version than the 1D version which he requested.
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