Re: [Boost-users] [random] getting a 50% probability generator

From: Brian Stadler (bdotstadler_at_[hidden])
Date: 2007-10-04 20:41:54

A few things,

First, try this when creating your uniform_01 object,

typedef boost::uniform_01<boost::mt19937> random_real;  <--you typedef'ed it
here.
random_real actual_generator;
actual_generator() <----to output numbers between 0 and 1.

Two,  don't use uniform_01.  The uniform_real class works much better and
defaults to between 0 and 1.

Three,  it looks like you are wanting random ints 0 and 1, not random real
numbers between 0 and 1.  For this have a look at the uniform_int or
uniform_smallint class.  They are probably what you are looking for.

Hope this helps.

Brian

On 10/4/07, Jeffrey Holle <jeffreyholle_at_[hidden]> wrote:
>
> I am at the point in my application where I must introduce randomness to
> a sort routine.  Basically when 2 elements are equal, I need to create a
> 50% probability that they will be swapped.
>
> What is the correct boost::random library resource to code this?
>
> I've attempted to use uniform_01, by creating an instance of it with
> this type:
>    typedef boost::uniform_01<boost::minstd_rand, double> rand_gen_t;
>
> However, after getting it constructed as a class attribute, I find
> accessing it with:
>    cout << (*pRand_gen++) << endl;
>
> It produces numbers like 1 134784888 134784288 2 134784845 134784224
> 134785176 5 0 134784376 134785328 0.
>
> What I want is a sequence like 0 1 0 1 0 1 0 0 0 1 1 1 1 0 1 0 1 that is
> sort of random.
>
>
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