Re: [Tutor] List append method: St Petersburg Game
bob gailer wrote:
On 2/20/2010 7:43 AM, AG wrote:
Please let me know how I can clarify my question
1 - You are giving way too much information. We do not need to know
the rules of the game or all the code. Our time to read email is
limited. The less you tell us that is not relevant the better.
Thanks Bob.
Also you don't show the code for the "next level of complexity".
Here it is, then:
import random
import matplotlib.pyplot as plt
import math
def flipCoin():
coinToss = random.randrange(1, 3)
return coinToss
toss_list = []
tosscounts = []
winnings = []
for i in range(0, 10):
while flipCoin() != 2:
toss_list.append("Tails")
flipCoin()
print
print "Heads"
tosscounts.append( len(toss_list))
if toss_list == 0:
print "You won $2"
winnings += 2
else:
toss_list.append( "Tail" )
winnings += [2 ** len( toss_list )]
print
print tosscounts
print winnings
print "Here's the graph: "
for i in winnings: # Convert int to float for log
i * 1.0
plt.plot( [tosscounts], [winnings] )
plt.ylabel( "how often" )
plt.xlabel( "how much" )
plt.show()
The result of the first call to flipCoin is ignored.
Each cycle of the loop results in 2 calls to flipCoin. The result of
the 2nd call is ignored.
Aha! Thanks for spotting that. Now fixed in the code cited above, but
still gives the same problem.
Thanks for any further ideas.
AG
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Re: [Tutor] List append method: St Petersburg Game
On 2/20/2010 7:43 AM, AG wrote:
Hi Pythonistas
I am having difficulty with applying the list.append(x) method to
produce a list that will contain outputs which will become coordinates
for a later call to Matplotlib. Perhaps someone here can help me
figure this out?
Please let me know how I can clarify my question
1 - You are giving way too much information. We do not need to know the
rules of the game or all the code. Our time to read email is limited.
The less you tell us that is not relevant the better. Also you don't
show the code for the "next level of complexity". What you should show
us is:
for i in range( 0, 10 ):
some lists are initialized and appended to. What are they and how are
they appended?
#Main function:
def flipCoin():
coinToss = random.randrange(1, 3)
return coinToss
# Storage of output
toss_list = []
# Get things going
flipCoin()
# Want to capture the coin lands heads (2)
while flipCoin() != 2:
toss_list.append("Tails")
flipCoin()
2 - The most obvious problem is here:
flipCoin()
while flipCoin() != 2:
toss_list.append("Tails")
flipCoin()
The result of the first call to flipCoin is ignored.
Each cycle of the loop results in 2 calls to flipCoin. The result of the
2nd call is ignored.
The overall purpose of the game is, for this discussion, irrelevant,
but some background info will be helpful I think. The above program
will give one run only and produces the output I expect.
Then your expectation is misguided, given my comments regarding multiple
calls to flipCoin! You don't actually know how many tosses were made!
[snip]
--
Bob Gailer
919-636-4239
Chapel Hill NC
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[Tutor] List append method: St Petersburg Game
Hi Pythonistas
I am having difficulty with applying the list.append(x) method to
produce a list that will contain outputs which will become coordinates
for a later call to Matplotlib. Perhaps someone here can help me figure
this out?
The basic program is below:
# St Petersburg Game: v. 2:
# Toss a coin. If it is heads, win $2, if not keep
# tossing it until it falls heads.
# Heads first toss = H = $2
# Heads third toss = TTH = $8
# Heads fifth toss = H = $32
# The game is to win more by not scoring Heads
print """St Petersburg Game: win multiples of $2 the
more you land Tails"""
# Required libraries
import random
import matplotlib.pyplot as plt
#Main function:
def flipCoin():
coinToss = random.randrange(1, 3)
return coinToss
# Storage of output
toss_list = []
# Get things going
flipCoin()
# Want to capture the coin lands heads (2)
while flipCoin() != 2:
toss_list.append("Tails")
flipCoin()
# Heads lands & show output
print
print "Heads"
print toss_list
# Interpret results & 'reward'
print "You flipped %d tails before landing Heads" % len(toss_list)
if toss_list == 0:
print "You won $2"
else:
toss_list.append( "Tail" )
print "You won $%d" % 2 ** len(toss_list)
The overall purpose of the game is, for this discussion, irrelevant, but
some background info will be helpful I think. The above program will
give one run only and produces the output I expect. When I take this to
the next level of complexity I run into problems.
1. I have tried to make this program run a given number of times, and
use the for repetition loop to do this, basically:
for i in range( 0, 10 ):
and then the above program is appropriately indented.
2. Collecting the number of coin "tosses" into a list appends these to a
list just fine. However, what this does is adds the numbers together so
that one ends up like this:
[0, 1, 2, 4, 5, 6, 8, 10, 11, 15]
With a corresponding increase in the values derived from multiplying the
exponent, thus:
[2, 4, 8, 32, 64, 128, 512, 2048, 4096, 65536]
Both are correct applications of the method, but I am unable to get the
list to not sum the values up in the first list, these are not
accumulative values, but discrete. If I am understanding what is
currently happening, the values are being accumulated, and I want to
stop that from happening.
If this isn't clear, please let me know how I can clarify my question to
help shape the relevance of the responses.
Thanks for any ideas.
AG
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