[Tutor] A file containing a string of 1 billion random digits.

[Richard D. Moores]

On Mon, Jul 19, 2010 at 04:51, Peter Otten <__peter__ at web.de> wrote:
> bob gailer wrote:
>
>> Check this out:
>>
>> import random, time
>> s = time.time()
>> cycles = 1000
>> d = "0123456789"*100
>> f = open("numbers.txt", "w")
>> for i in xrange(n):
>>    l = []
>>    l.extend(random.sample(d, 1000))
>>    f.write(''.join(l))
>> f.close()
>> print time.time() - s
>
> Note that this is not random. E. g. the start sequence "0"*101 should have a
> likelyhood of 1/10**101 but is impossible to generate with your setup.
I not sure exactly what you mean, because I don't fully understand
that '*' (despite Alan's patient explanation), but if you run

import random
cycles = 100000
d = "0123456789"*10
for i in range(cycles):
   l = []
   l.extend(random.sample(d, 100))
   s = (''.join(l))
   if s[:4] == '0101':
       print(s)

You'll see a bunch of strings that begin with "0101"

Or if you run

import random
cycles = 50
d = "0123456789"*10
for i in range(cycles):
   l = []
   l.extend(random.sample(d, 100))
   s = (''.join(l))
   if s[:1] == '0':
       print(s)

You'll see some that begin with '0'.

Am I on the right track?

Dick