how to create array of random normalize number?

Question

i want to create a matrix that each row of the matrix have 7 real random number in [0,1] and the sum of number in each rows should be equal to 1. this matrix have 100 rows and 7 columns. how can i do it? at first ,i create an array with 1 row and 7 columns. then write the code as bellow. i try normal the number in the rows but sum of each row became more than 1.how can i fix it? thank for taking your time.

a = rand(1,7);
for i=1:7
a(i) = a(i)/sum(a);
end
sum(a)

If you additionally want each row to be uniformly distributed (you don't specify) you need an approach like this. Generating statistically independent samples and dividing by the obtained sum won't work — Luis Mendo
– Luis Mendo, Commented Jul 6, 2017 at 10:28

Yacine · Accepted Answer · 2017-07-06 11:49:43Z

4

For 100 by 7, you can use bsxfun:

a = rand(100,7);
a = bsxfun(@rdivide,a.',sum(a.')).';

Here the sum of each row = 1

edited Jul 6, 2017 at 11:49

answered Jul 6, 2017 at 7:42

Yacine

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MrAzzaman · Accepted Answer · 2017-07-06 07:35:27Z

2

The problem is that by using a for-loop, you're changing the sum of the vector every loop iteration. You should take advantage of MATLAB's ability to act on whole matrices at once:

a = rand(1,7);
a = a./sum(a);

answered Jul 6, 2017 at 7:35

MrAzzaman

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