[Tutor] Need help with random numbers

[Danny Yoo]

On Tue, 17 Jul 2001, kevin parks wrote:

> Since it has be brought up, I'd like to know:
> 
> random.random() takes no args and returns a float in the range
> 0.0-1.0. How would you return random floats of a different range? say:
> 1.0 - 12.0?
> 
> random() 
>        Return the next random floating point number in the range [0.0,
> 1.0).

There's a good reason why random.random() gives us a floating point
between 0.0 and 1.0: it allows us to "scale" it up to a larger range if we
need it.  For example, to get a random float between 0.0 and 10.0 (more
precisely, "[0.0, 10.0)" ), we can do this:

    some_number = random.random() * 10.0

It's like "stretching" the random function.


I'm curious: how does random.uniform() actually work?

###
    def uniform(self, a, b):
        """Get a random number in the range [a, b)."""
        return a + (b-a) * self.random()
###

Yup, that's how they do it as well.  They do a little bit more to move the
range from:

    [0, b-a)
to
    [a, b)

but otherwise, they use the stretching principle.


Hope this helps!