beginner code problem

[Rob Johnson]

On 2006-06-02 19:25:28 -0400, John Machin <sjmachin at lexicon.net> said:

> Thanks for the reply John. I seem to be getting all the same problems 
> with your code that I had with mine so it may be an issue with Python 
> on this computer though I haven't had one prior to now. I'm running it 
> on OSX Tiger so I'll give it a shot on my Windows box. With pythons 
> portability I didn't think it would be an issue so didn't mention it in 
> the post.

   The different problems I was having was a result of moving some of 
the code around thinking I had messed up and trying to fix it. The code 
I posted was just running but never stopping to give the the output.

  Thanks for explaining about getting a new value for flip, I wasn't 
positive about that and you really helped clear up any confusion I was 
having.

 Rob

> 
> This can't happen with the code that you posted. It *could* happen if 
> the statement count += 1 was not being executed once each time around 
> the while loop -- like if it was *not* indented.
> 
> # Bad code #1
> import random
> flip = random.randrange(2)
> heads = tails = count = 0
> while count < 100:
>      if flip == 0:
>          heads += 1
>      else:
>          tails += 1
> count += 1
> print "The coin landed on heads", heads, 'times ' \
> 	"and tails", tails, 'times'
> 
>> A few times I would get it to print 'heads 0 (or 1) times and tails 1 
>> (or 0) times' 100 times.
> 
> Again, can't happen with the code you have posted. If it is printing 
> 100 times, that would be because you have indented the print statement 
> so that it is being executed once each trip around the loop.
> 
> # Bad code #2
> import random
> flip = random.randrange(2)
> heads = tails = count = 0
> while count < 100:
>      if flip == 0:
>          heads += 1
>      else:
>          tails += 1
>      count += 1
>      print "The coin landed on heads", heads, 'times ' \
>          "and tails", tails, 'times'
> 
>> 
>> Here's the code I wrote:
>> 
>> import random
>> 
>> flip = random.randrange(2)
>> heads = 0
>> tails = 0
>> count = 0
>> 
>> while count < 100:
> 
> To help you see what is happening, insert a print statement here; e.g.:
>      print flip, count, heads, tails
>> 
>>     if flip == 0:
>>         heads += 1
>>         else:
>>         tails += 1
>> 
>>     count += 1
>> 
>> print "The coin landed on heads", heads, 'times ' \
>>         "and tails", tails, 'times'
>> 
> 
> The code that you posted sets flip only once i.e. only 1 toss, not 100. 
> If it is 0, you get 100 heads and 0 tails. Otherwise you get 0 heads 
> and 100 tails. You need to get a new value for flip each trip.
> 
> # Not quite so bad code
> import random
> heads = tails = count = 0
> while count < 100:
>      flip = random.randrange(2)
>      # print flip, count, heads, tails # un-comment as/when required :-)
>      if flip == 0:
>          heads += 1
>      else:
>          tails += 1
>      count += 1
> print "The coin landed on heads", heads, 'times ' \
>      "and tails", tails, 'times'
> 
> HTH,
> John