Beginners Query - Simple counter problem

[David Barr]

I am brand new to Python (this is my second day), and the only
experience I have with programming was with VBA. Anyway, I'm posting
this to see if anyone would be kind enough to help me with this (I
suspect, very easy to solve) query.

The following code is in a file which I am running through the
interpreter with the execfile command, yet it yeilds no results. I
appreciate I am obviously doing something really stupid here, but I
can't find it. Any help appreciated.


def d6(i):
roll = 0
count = 0
while count <= i:
roll = roll + random.randint(1,6)
count += 1

return roll

print d6(3)

 

[Scott David Daniels]

I am brand new to Python (this is my second day), and the only
experience I have with programming was with VBA. Anyway, I'm posting
this to see if anyone would be kind enough to help me with this (I
suspect, very easy to solve) query.

The following code is in a file which I am running through the
interpreter with the execfile command, yet it yeilds no results. I
appreciate I am obviously doing something really stupid here, but I
can't find it. Any help appreciated.


def d6(i):
roll = 0
count = 0
while count <= i:
roll = roll + random.randint(1,6)
count += 1

return roll

print d6(3)

A) your direct answer: by using <=, you are rolling 4 dice, not 3.
B) Much more pythonic:

import random

def d6(count):
result = 0
for die in range(count):
result += random.randint(1, 6)
return result

-Scott David Daniels
(e-mail address removed)

 

[Carsten Haese]

def d6(count):
result = 0
for die in range(count):
result += random.randint(1, 6)
return result

This, of course, can be further improved into:

def d6(count):
return sum(random.randint(1, 6) for die in range(count))

 

[Ian Clark]

This, of course, can be further improved into:

def d6(count):
return sum(random.randint(1, 6) for die in range(count))

My stab at it:
... return random.randint(times, times*sides)

Ian

 

[Carsten Haese]

My stab at it:

... return random.randint(times, times*sides)

That produces an entirely different probability distribution if times>1.
Consider times=2, sides=6. Your example will produce every number
between 2 and 12 uniformly with the same probability, 1 in 11. When
rolling two six-sided dice, the results are not evenly distributed. E.g.
the probability of getting a 2 is only 1 in 36, but the probability of
getting a 7 is 1 in 6.

 

[Ian Clark]

That produces an entirely different probability distribution if times>1.
Consider times=2, sides=6. Your example will produce every number
between 2 and 12 uniformly with the same probability, 1 in 11. When
rolling two six-sided dice, the results are not evenly distributed. E.g.
the probability of getting a 2 is only 1 in 36, but the probability of
getting a 7 is 1 in 6.

Doh. I stand corrected. Probability was never a fun subject for me.

Ian

 

[David Barr]

A) your direct answer: by using <=, you are rolling 4 dice, not 3.
B) Much more pythonic:

import random

def d6(count):
result = 0
for die in range(count):
result += random.randint(1, 6)
return result

-Scott David Daniels
(e-mail address removed)

I was surprised by the speed and number of posts. Thanks for the
solutions provided!
.... return random.randint(times, times*sides)

Although this would probably be quicker than the other approaches, I'm
not using the dice to generate numbers per say, I actually want to
emulate the rolling of dice, bell-curve (normal distribution) as well as
the range.

Thanks again, I already like what (very) little I can do in Python and
it seems to have a great community too.

Cheers,
Dave.

 

[Zentrader]

yields no results.

Since every response so far has answered everything __Except The
Question You Asked__, your code runs fine on my Linux machine and
prints 15. The error may be before this bit of code so it isn't
getting called. Add some print statements and try again

def d6(i):
print "start of d6()"
roll = 0
count = 0
while count <= i:
print "d6 count =", count, "of", i
roll = roll + random.randint(1,6)
count += 1

print "returning roll =", roll
return roll

print d6(3)

 

[mensanator]

That produces an entirely different probability distribution if times>1.
Consider times=2, sides=6. Your example will produce every number
between 2 and 12 uniformly with the same probability, 1 in 11. When
rolling two six-sided dice, the results are not evenly distributed. E.g.
the probability of getting a 2 is only 1 in 36, but the probability of
getting a 7 is 1 in 6.

Why settle for a normal distribution?

import random

def devildice(dice):
return sum([random.choice(die) for die in dice])

hist = {}

for n in xrange(10000):
the_key = devildice([[1,2,3,10,11,12],[4,5,6,7,8,9]])
if the_key in hist:
hist[the_key] += 1
else:
hist[the_key] = 1

hkey = hist.keys()
m = max(hkey)
n = min(hkey)
histogram = [(i,hist.get(i,0)) for i in xrange(n,m+1)]
for h in histogram:
print '%3d %s' % (h[0],'*'*(h[1]/100))

## 5 **
## 6 *****
## 7 ********
## 8 ********
## 9 ********
## 10 *******
## 11 *****
## 12 **
## 13
## 14 **
## 15 ******
## 16 ********
## 17 ********
## 18 ********
## 19 ********
## 20 *****
## 21 **

They're called Devil Dice because the mean is 13 even
though you cannot roll a 13.

 

[Dennis Lee Bieber]

The following code is in a file which I am running through the
interpreter with the execfile command, yet it yeilds no results. I
appreciate I am obviously doing something really stupid here, but I
can't find it. Any help appreciated.

Many responses on coding the d6 function... But I have to ask: WHY
are you using execfile!
--
Wulfraed Dennis Lee Bieber KD6MOG
(e-mail address removed) (e-mail address removed)
HTTP://wlfraed.home.netcom.com/
(Bestiaria Support Staff: (e-mail address removed))
HTTP://www.bestiaria.com/