# Randomly splitting of a number in a sum format.

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rohini more on 27 Apr 2021
Commented: rohini more on 27 Apr 2021
Suppose n=5
we can split this number like
5=3+2,4+1..... so on.
But I just want to select a only one sum but randomly and I would like to specify by using varible
like
5=1+3+1
then n_{1}=1, n_{2}=3, n_{3}=1.
How to implement matlab code for any value of n as per above method.
##### 2 CommentsShowHide 1 older comment
John D'Errico on 27 Apr 2021
No. There have been multiple questions about random partitions of a set. Learn how to find the set of all partitions, then choose one randomly. You cannot create variable names on the fly, and to the extent that you can do so, you SHOULD not. Instead, learn to use vectors.

Bruno Luong on 27 Apr 2021
Edited: Bruno Luong on 27 Apr 2021
n = 10;
for j=1:10
r = n;
i = 1;
clear s
while r > 0
s(i) = ceil(r*rand);
r = r-s(i);
i = i+1;
end
disp(s)
end
4 2 4 8 1 1 7 3 4 2 2 1 1 8 1 1 7 1 1 1 7 1 1 1 10 8 2 1 9
rohini more on 27 Apr 2021
Now its working . Thank you very much.

Bruno Luong on 27 Apr 2021
Edited: Bruno Luong on 27 Apr 2021
This code will generate "uniform" partition distribution, in the sense that all possible partition has equal probability:
n = 10;
% This part is done once if n is fix
L = 1:n;
p = arrayfun(@(k) nchoosek(n-1,n-k), L);
e = [0, cumsum(p)];
e = e/e(end);
% This part must be repeated when an new random partition is requested
[~,k] = histc(rand,e);
h = diff([0 sort(randperm(n-1,n-k)) n]);
H = mat2cell(L, 1, h)
H = 1×2 cell array
{[1 2 3 4 5]} {[6 7 8 9 10]}
rohini more on 27 Apr 2021
Thanks for giving your valuable time for solving my question. It really means a lot.
Thank you very much.