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Diffstat (limited to 'Doc/library/random.rst')
| -rw-r--r-- | Doc/library/random.rst | 34 |
1 files changed, 29 insertions, 5 deletions
diff --git a/Doc/library/random.rst b/Doc/library/random.rst index 43c07dd..5492346 100644 --- a/Doc/library/random.rst +++ b/Doc/library/random.rst @@ -345,8 +345,8 @@ Basic examples:: >>> randrange(0, 101, 2) # Even integer from 0 to 100 inclusive 26 - >>> choice('abcdefghij') # Single random element from a sequence - 'c' + >>> choice(['win', 'lose', 'draw']) # Single random element from a sequence + 'draw' >>> deck = 'ace two three four'.split() >>> shuffle(deck) # Shuffle a list @@ -370,8 +370,9 @@ Simulations:: >>> print(seen.count('tens') / 20) 0.15 - # Estimate the probability of getting 5 or more heads from 7 spins - # of a biased coin that settles on heads 60% of the time. + # Estimate the probability of getting 5 or more heads + # from 7 spins of a biased coin that settles on heads + # 60% of the time. >>> n = 10000 >>> cw = [0.60, 1.00] >>> sum(choices('HT', cum_weights=cw, k=7).count('H') >= 5 for i in range(n)) / n @@ -416,4 +417,27 @@ between the effects of a drug versus a placebo:: print(f'{n} label reshufflings produced only {count} instances with a difference') print(f'at least as extreme as the observed difference of {observed_diff:.1f}.') print(f'The one-sided p-value of {count / n:.4f} leads us to reject the null') - print(f'hypothesis that the observed difference occurred due to chance.') + print(f'hypothesis that there is no difference between the drug and the placebo.') + +Simulation of arrival times and service deliveries in a single server queue:: + + from random import gauss, expovariate + + average_arrival_interval = 5.6 + average_service_time = 5.0 + stdev_service_time = 0.5 + + num_waiting = 0 + arrival = service_end = 0.0 + for i in range(10000): + num_waiting += 1 + arrival += expovariate(1.0 / average_arrival_interval) + print(f'{arrival:6.1f} arrived') + + while arrival > service_end: + num_waiting -= 1 + service_start = service_end if num_waiting else arrival + service_time = gauss(average_service_time, stdev_service_time) + service_end = service_start + service_time + print(f'\t\t{service_start:.1f} to {service_end:.1f} serviced') + |