[Tutor] Giving a name to a function and calling it, rather than calling the function directly

[lists]

>  On 9/4/2010 10:14 AM, lists wrote:
>>
>> Hi folks,
>>
>> I'm new to Python, I'm working my way through some intro books, and I
>> have a question that I wonder if someone could help me with please?
>>
>> This is my attempt at solving an exercise where the program is
>> supposed to flip a coin 100 times and then tell you the number of
>> heads and tails.
>>
>> ATTEMPT 1 returns:
>>
>> The coin landed on tails 100 times
>>
>> The coin landed on heads 0 times
>>
>> ATTEMPT 2 returns:
>>
>> The coin landed on tails 75 times
>>
>> The coin landed on heads 25 times
>>
>> I expected to see the result in attempt 2. I don't fully understand
>> why the results are different however. Is it because Python only runs
>> the randint function once when I call it by the name I assigned to it
>> in attempt 1, but it runs the function fully on each iteration of the
>> loop in attempt 2? Why are these two things different?
>>
>> Thanks in advance,
>>
>> Chris
>> ------------------------------------------------------------------
>> ATTEMPT 1
>> ------------------------------------------------------------------
>> import random
>>
>> heads = 0
>> tails = 0
>> tossNo = 0
>> toss = random.randint(1,2)
>>
>> while tossNo<= 99:
>>     if toss == 1:
>>         heads += 1
>>         tossNo += 1
>>     elif toss == 2:
>>          tails += 1
>>          tossNo += 1
>>
>> print "The coin landed on tails " + str(tails) + " times \n"
>> print "The coin landed on heads " + str(heads) + " times \n"
>>
>> ------------------------------------------------------------------
>> ATTEMPT 2
>> ------------------------------------------------------------------
>> import random
>>
>> heads = 0
>> tails = 0
>> tossNo = 0
>>
> You should have only 1 call to randint in the loop
>>
>> while tossNo<= 99:
>>     if random.randint(1,2) == 1:
>>         heads += 1
>>         tossNo += 1
>>     else:
>>          tails += 1
>>          tossNo += 1
>>
>> print "The coin landed on tails " + str(tails) + " times \n"
>> print "The coin landed on heads " + str(heads) + " times \n"
>
> You can also simplify:
>
> import random
> heads = 0
> tosses = 100
> for i in range(tosses):
>    heads += random.randint(0,1)
> print "The coin landed on tails " + str(tosses - heads) + " times \n"
> print "The coin landed on heads " + str(heads) + " times \n"
>
> Or even simpler:
>
> import random
> tosses = 100
> heads = sum(random.randint(0,1) for i in range(tosses))
> print ...
>
>
> --
> Bob Gailer
> 919-636-4239
> Chapel Hill NC
>

Thanks again all! Hopefully as I learn more I'll find it easier to
make the most efficient design choices :-)

Chris