Basic coin flipper program - logical error help

[DannyB]

I'm just learning Python. I've created a simple coin flipper program -
here is the code:

[source]
#Coin flipper
import random

heads = 0
tails = 0
counter = 0

coin = random.randrang e(2)

while (counter < 100):
if (coin == 0):
heads += 1
counter += 1
else:
tails += 1
counter += 1

coin = random.randrang e(2)
print "\nThe coin landed on heads", heads, "times."
print "\nThe coin landed on tails", tails, "times."
[/source]

<<<I'm sure the [source] tags don't work - I through them in there
anyway.>>>

The program runs - however - it will give me 100 heads OR 100 tails.
Can someone spot the logic error?

Thanks

~Dan

[Jeffrey Schwab]

wes weston wrote:

DannyB wrote:

I'm just learning Python. I've created a simple coin flipper program -

....
Dan,
Looping is easier with:
for x in range(100):
if random.randint( 0,1) == 0:
heads += 1
else:
tails += 1

Or, continuing with that theme:

for x in range(N):
heads += random.randint( 0, 1)

As in:

import random
N = 100
heads = 0
for x in range(N):
heads += random.randint( 0, 1)
print "%d heads and %d tails." % (heads, N - heads)

[Brian van den Broek]

DannyB said unto the world upon 21/02/06 06:14 PM:

I'm just learning Python. I've created a simple coin flipper program -
here is the code:

[source]
#Coin flipper
import random

heads = 0
tails = 0
counter = 0

coin = random.randrang e(2)

while (counter < 100):
if (coin == 0):
heads += 1
counter += 1
else:
tails += 1
counter += 1

coin = random.randrang e(2)
<snip>

The program runs - however - it will give me 100 heads OR 100 tails.
Can someone spot the logic error?

<snip>

Your original question is long since answered. But I've a style point.
As Dennis Lee Bieber pointed out, you don't need all three
accumulators. If you keep to the overall style of your code, you can
avoid repeating yourself as:
while (counter < 100):
counter += 1 # No point in putting this in each branch
coin = random.randrang e(2)
if (coin == 0):
heads += 1
else:
tails += 1
For roughly the same style, I'd go with:

heads = 0
count = 100

for i in range(count):
if random.randrang e(2):
heads += 1

tails = count - heads

HTH,

Brian vdB

[Paul McGuire]

"Paul McGuire" <pt***@austin.r r._bogus_.com> wrote in message
news:yU******** **********@torn ado.texas.rr.co m...

<bo****@gmail.c om> wrote in message
news:11******** **************@ g43g2000cwa.goo glegroups.com.. . sort, then groupby.
import itertools
import random
h,t = [len(list(g)) for k,g in itertools.group by(sorted([random.randrang e(2) for i in xrange(100)]))]
print h,t

By the way, sort + groupby generalizes beyond just coin-flipping. Here is a
modified version that simulates die rolls.

-- Paul

import itertools
import random

NUM_ROLLS = 1000
dieRolls = [random.randrang e(6)+random.ran drange(6)+2 for i in
xrange(NUM_ROLL S)]

# create dummy list entries for impossible rolls of 0 and 1
rolls = [None,None]

rolls += [len(list(g)) for k,g in itertools.group by(sorted(dieRo lls))]

# print out nice histogram
for i,r in enumerate(rolls ):
if i > 1:
print "%2d - %s" % (i,"*"*int(roun d(r/10.0)))
prints:

2 - ***
3 - *****
4 - *********
5 - **********
6 - ***************
7 - *************** ***
8 - **************
9 - *********
10 - *******
11 - *******
12 - ***