python随机数

package

import random

randint()

函数原型

randint(self, a, b) method of Random instance
Return random integer in range [a, b], including both end points.

示例

Python 2.7.11 (v2.7.11:6d1b6a68f775, Dec  5 2015, 20:32:19) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import random>>> print random.randint(1,2)
1
>>> print random.randint(1,2)
2
>>> print random.randint(100,200)
116
>>> import sys
>>> print random.randint(int(sys.maxint), sys.maxint)
2147483647
>>> print sys.maxint
2147483647
>>> print random.randint(int(sys.maxint / 10), sys.maxint)
1622687942
>>>

random doc

betavariate(self, alpha, beta) method of Random instance
Beta distribution.

Conditions on the parameters are alpha > 0 and beta > 0.
Returned values range between 0 and 1.

choice(self, seq) method of Random instance
Choose a random element from a non-empty sequence.

expovariate(self, lambd) method of Random instance
Exponential distribution.

lambd is 1.0 divided by the desired mean.  It should be
nonzero.  (The parameter would be called "lambda", but that is
a reserved word in Python.)  Returned values range from 0 to
positive infinity if lambd is positive, and from negative
infinity to 0 if lambd is negative.

gammavariate(self, alpha, beta) method of Random instance
Gamma distribution.  Not the gamma function!

Conditions on the parameters are alpha > 0 and beta > 0.

The probability distribution function is:

x ** (alpha - 1) * math.exp(-x / beta)
pdf(x) =  --------------------------------------
math.gamma(alpha) * beta ** alpha

gauss(self, mu, sigma) method of Random instance
Gaussian distribution.

mu is the mean, and sigma is the standard deviation.  This is
slightly faster than the normalvariate() function.

Not thread-safe without a lock around calls.

getrandbits(...)
getrandbits(k) -> x.  Generates a long int with k random bits.

getstate(self) method of Random instance
Return internal state; can be passed to setstate() later.

jumpahead(self, n) method of Random instance
Change the internal state to one that is likely far away
from the current state.  This method will not be in Py3.x,
so it is better to simply reseed.

lognormvariate(self, mu, sigma) method of Random instance
Log normal distribution.

If you take the natural logarithm of this distribution, you'll get a
normal distribution with mean mu and standard deviation sigma.
mu can have any value, and sigma must be greater than zero.

normalvariate(self, mu, sigma) method of Random instance
Normal distribution.

mu is the mean, and sigma is the standard deviation.

paretovariate(self, alpha) method of Random instance
Pareto distribution.  alpha is the shape parameter.

randint(self, a, b) method of Random instance
Return random integer in range [a, b], including both end points.
random(...)
random() -> x in the interval [0, 1).

randrange(self, start, stop=None, step=1, _int=<type 'int'>, _maxwidth=9007199254740992L) method of Random instance
Choose a random item from range(start, stop[, step]).

This fixes the problem with randint() which includes the
endpoint; in Python this is usually not what you want.

sample(self, population, k) method of Random instance
Chooses k unique random elements from a population sequence.

Returns a new list containing elements from the population while
leaving the original population unchanged.  The resulting list is
in selection order so that all sub-slices will also be valid random
samples.  This allows raffle winners (the sample) to be partitioned
into grand prize and second place winners (the subslices).

Members of the population need not be hashable or unique.  If the
population contains repeats, then each occurrence is a possible
selection in the sample.

To choose a sample in a range of integers, use xrange as an argument.
This is especially fast and space efficient for sampling from a
large population:   sample(xrange(10000000), 60)

seed(self, a=None) method of Random instance
Initialize internal state from hashable object.

None or no argument seeds from current time or from an operating
system specific randomness source if available.

If a is not None or an int or long, hash(a) is used instead.

setstate(self, state) method of Random instance
Restore internal state from object returned by getstate().

shuffle(self, x, random=None) method of Random instance
x, random=random.random -> shuffle list x in place; return None.

Optional arg random is a 0-argument function returning a random
float in [0.0, 1.0); by default, the standard random.random.

triangular(self, low=0.0, high=1.0, mode=None) method of Random instance
Triangular distribution.

Continuous distribution bounded by given lower and upper limits,
and having a given mode value in-between.
 http://en.wikipedia.org/wiki/Triangular_distribution 
uniform(self, a, b) method of Random instance
Get a random number in the range [a, b) or [a, b] depending on rounding.

vonmisesvariate(self, mu, kappa) method of Random instance
Circular data distribution.

mu is the mean angle, expressed in radians between 0 and 2*pi, and
kappa is the concentration parameter, which must be greater than or
equal to zero.  If kappa is equal to zero, this distribution reduces
to a uniform random angle over the range 0 to 2*pi.

weibullvariate(self, alpha, beta) method of Random instance
Weibull distribution.

alpha is the scale parameter and beta is the shape parameter.