When using random, which form returns an equal 50% chance?

Question

I'm guessing that most built in random generators return something like this:

[0.0, 1.0)

so if I would like a 50% chance would I use something like this:

if random() < .5

or something like:

if random() <= .5

Thanks for the help.

Answer 1

Why do it yourself? Python has random.choice :)

random.choice([0, 1]) will give you 0/1 with equal chances -- and it is a standard part of Python, coded up by the same people who wrote random.random (and thus know more about its semantics than anyone else)

Answer 2

Ah, the old ".5" problem. Here's the answer:

If you're going to divide 10 things into two equal parts, you need 5 things in each part. 0 thru 4 in the first part, 5-9 in the second part. So... < .5 is correct.

Answer 3

To a first approximation, either works.

The best way is to choose a random generator that specifically emits booleans or integers with range. Then you can nail the range exactly.

Operations like "equality" with floating point is iffy anyway.