python生成和为1的随机数_生成一个总和为1的随机数序列？

I am at my wit''s end.

I want to generate a certain number of random numbers.

This is easy, I can repeatedly do uniform(0, 1) for

example.

But, I want the random numbers just generated sum up

to 1 .

I am not sure how to do this. Any idea? Thanks.

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解决方案Anthony Liu wrote:I am at my wit''s end.

I want to generate a certain number of random numbers.

This is easy, I can repeatedly do uniform(0, 1) for

example.

But, I want the random numbers just generated sum up

to 1 .

I am not sure how to do this. Any idea? Thanks.

numbers.append (random.uniform (0, 1.0-sum(numbers)))

might help, perhaps.

or

scaled = [x/sum(numbers) for x in numbers]

Mel.

Anthony Liu wrote:But, I want the random numbers just generated sum up

to 1 .

This seems like an odd request. Might I ask what it''s for?

Generating random numbers in [0,1) that are both uniform and sum to 1 looks

like an unsatisfiable task. Each number you generate restricts the

possibilities for future numbers. E.g. if the first number is 0.5, all

future numbers must be < 0.5 (indeed, must *sum* to 0.5). You''ll end up

with a distribution increasingly skewed towards smaller numbers the more

you generate. I can''t imagine what that would be useful for.

If that''s not a problem, do this: generate the numbers, add them up, and

divide each by the sum.

nums = [random.uniform(0,1) for x in range(0,100)]

sum = reduce(lambda x,y: x+y, nums)

norm = [x/sum for x in nums]

Of course now the numbers aren''t uniform over [0,1) anymore.

Also note that the sum of the normalized numbers will be very close to 1,

but slightly off due to representation issues. If that level of accuracy

matters, you might consider generating your rands as integers and then

fp-dividing by the sum (or just store them as integers/fractions).

Em S??b, 2006-04-22 ?*s 03:16 +0000, Edward Elliott escreveu:If that level of accuracy

matters, you might consider generating your rands as integers and then

fp-dividing by the sum (or just store them as integers/fractions).

Or using decimal module: http://docs.python.org/lib/module-decimal.html

--

Felipe.