[Tutor] Need help understanding output...

[Laurens Vets]

On 8/12/2010 1:26 AM, Steven D'Aprano wrote:
> On Thu, 12 Aug 2010 07:04:15 am Laurens Vets wrote:
>
>> I need to generate a list of 30 numbers randomly chosen from 1, 2, 3,
>> 4, 5&  6. However, I cannot have more than 2 numbers which are the
>> same next to each other. I came up with the following (Please ignore
>> the fact that I'm trying to avoid an IndexError in a stupid way :)):
>
> I can't possible do that! :)
>
>> import random
>> reeks = []
>> while len(reeks)<= 1:
>>     number = random.randrange(1, 7, 1)
>>     reeks.append(number)
>>
>> while len(reeks)<= 29:
>>     nummer = random.randrange(1, 7, 1)
>>     if nummer != reeks[-1] and nummer != reeks[-2]:
>>       reeks.append(nummer)
>> print reeks
>
> This is probably a simpler way:
>
> import random
> reeks = []
> for i in range(30):
>      temp = [random.randint(1, 6)]
>      while reeks[-2:-1] == reeks[-1:] == temp:
>          # print "Triplet found:", reeks, temp
>          temp = [random.randint(1, 6)]
>      reeks.extend(temp)
>
> print reeks

<snip>

Thank you all for your help! I've added another condition to this 
program, namely, in a range of 60, each 'random' number can only occur 
10 times. I came up with the following:

import random
series = []
for i in range(60):
   temp = [random.randint(1, 6)]
   while series[-2:-1] == series[-1:] == temp:
     temp = [random.randint(1, 6)]
   while series.count(temp[0]) >= 10:
     temp = [random.randint(1, 6)]
   series.extend(temp)
print series

However, this also generates gems such as:

[4, 4, 3, 6, 3, 2, 6, 3, 4, 3, 4, 1, 4, 2, 4, 3, 4, 4, 6, 2, 1, 5, 5, 6, 
5, 6, 5, 6, 3, 3, 1, 6, 6, 4, 1, 5, 2, 6, 6, 4, 2, 5, 3, 1, 5, 5, 2, 1, 
_2_, _2_, _2_, 3, 3, 2, 1, 5, 1, 1, 5, 1]

[1, 4, 3, 1, 5, 3, 5, 1, 5, 6, 5, 3, 2, 6, 1, 4, 1, 5, 5, 2, 6, 2, 4, 1, 
3, 1, 2, 1, 1, 3, 1, 6, 6, 3, 2, 3, 6, 4, 5, 6, 5, 6, 3, 6, 2, 4, 5, 3, 
3, 4, 6, _4_, _4_, _4_, 5, 4, _2_, _2_, _2_, _2_]

I thought this needed to become the following:

import random
series = []
for i in range(60):
   temp = [random.randint(1, 6)]
   print "Temp", i, ":", temp
   while series[-2:-1] == series[-1:] == series:
     if series.count(temp[0]) >= 10:
       temp = [random.randint(1, 6)]
   series.extend(temp)
print series

But this just hangs whenever the while clause matches. I'm not sure what 
I'm doing wrong here. I do know the random.shuffle() function, but I 
can't put my conditions in there.

Any push in the right direction would be greatly appreciated :)