on writing a while loop for rolling two dice

[Peter Otten]

On 28/08/2021 14:00, Hope Rouselle wrote:

> def how_many_times():
>    x, y = 0, 1
>    c = 0
>    while x != y:
>      c = c + 1
>      x, y = roll()
>    return c, (x, y)
> --8<---------------cut here---------------end--------------->8---
> 
> Why am I unhappy?  I'm wish I could confine x, y to the while loop.  The
> introduction of ``x, y = 0, 1'' must feel like a trick to a novice.  How
> would you write this?  Thank you!

I'd probably hide the while loop under the rug:

 >>> import random
 >>> def roll_die():
	while True: yield random.randrange(1, 7)

	
Then:

 >>> def hmt():
	for c, (x, y) in enumerate(zip(roll_die(), roll_die()), 1):
		if x == y:
			return c, (x, y)

		
 >>> hmt()
(1, (2, 2))
 >>> hmt()
(4, (4, 4))
 >>> hmt()
(1, (5, 5))


OK, maybe a bit complicated... but does it pay off if you want to 
generalize?

 >>> def roll_die(faces):
	while True: yield random.randrange(1, 1 + faces)

 >>> def hmt(faces, dies):
	for c, d in enumerate(zip(*[roll_die(faces)]*dies), 1):
		if len(set(d)) == 1: return c, d

		
 >>> hmt(10, 1)
(1, (2,))
 >>> hmt(10, 2)
(3, (10, 10))
 >>> hmt(10, 3)
(250, (5, 5, 5))
 >>> hmt(1, 10)
(1, (1, 1, 1, 1, 1, 1, 1, 1, 1, 1))

You decide :)