python随机函数

random, uniform, randint, randrange, shuffle, sample

1. random()

   random():返回随机生成的一个实数，范围[0,1)

   import random  #random()方法不能直接访问，需要导入random模块，然后通过random静态对象调用该方法
   

   • 1

2. random.random()

   random.random()方法用于生成一个0到1的随机浮点数：0<=n<=1.0

   Python 3.7.9 (default, Aug 31 2020, 17:10:11) [MSC v.1916 64 bit (AMD64)] :: Anaconda, Inc. on win32
   Type "help", "copyright", "credits" or "license" for more information.
   
   >>> import random
   >>> print(random.random())
   0.9813106591730276
   >>> print(random.random())
   0.7331968297842003
   

   • 1
   • 2
   • 3
   • 4
   • 5
   • 6
   • 7
   • 8

3. random.uniform

   random.uniform(a,b):用于生成一个指定范围内的随机浮点数。如果a>b，则b<=n<=a; 若a>b,则a<=n<=b.

   >>> import random
   >>> print(random.uniform(4,10))
   5.766155005725524
   >>> print(random.uniform(10,4))
   6.253381814573553
   

   • 1
   • 2
   • 3
   • 4
   • 5

4. random.randint

   random.randint(a,b), 用于生成一个指定范围内的整数，必须满足a<=b,生成随机数n: a<=n<=b

   >>> import random
   >>> print(random.randint(5,10))
   8
   >>> print(random.randint(5,5))
   5
   >>> print(random.randint(5,1))	# 报错
   Traceback (most recent call last):
     File "<stdin>", line 1, in <module>
     File "D:\Anaconda3\lib\random.py", line 222, in randint
       return self.randrange(a, b+1)
     File "D:\Anaconda3\lib\random.py", line 200, in randrange
       raise ValueError("empty range for randrange() (%d,%d, %d)" % (istart, istop, width))
   ValueError: empty range for randrange() (5,2, -3)
   

   • 1
   • 2
   • 3
   • 4
   • 5
   • 6
   • 7
   • 8
   • 9
   • 10
   • 11
   • 12
   • 13

5. random.randrange

   random.randrange(start, stop，step): 从指定范围内，按指定基数递增的集合中获取一个是随机数，如random.randrange(10, 20, 2)，结果相当于从[10,12,14,16,18]中获取一个随机数。结果上与random.choice(range(10,20,2))一致

   >>> import random
   >>> print(random.randrange(10,20,2))
   14
   >>> print(random.randrange(10,12,2))
   10
   

   • 1
   • 2
   • 3
   • 4
   • 5

6. random.choice

   random.choice(sequence): sequence表示一个有序类型。sequence在python不是一种特定的类型，而是泛指一系列的类型：list, tuple, 字符串等

   >>> import random
   >>> print (random.choice("喜欢Python？"))
   t
   >>> print (random.choice("喜欢Python？"))
   喜
   >>> print(random.choice(["Joob","python","bodd"]))
   bodd
   >>> print(random.choice(["Joob","python","bodd"]))
   python
   >>> print(random.choice(("Tuple", "List", "Dicti")))
   List
   >>> print(random.choice(("Tuple", "List", "Dicti")))
   Dicti
   

   • 1
   • 2
   • 3
   • 4
   • 5
   • 6
   • 7
   • 8
   • 9
   • 10
   • 11
   • 12
   • 13

7. random.shuffle

   random.shuffle(x[,random]): 用于将一个列表中的元素打乱

   >>> import random
   >>> p = ["Joob","python","bodd"]
   >>> random.shuffle(p)
   >>> p
   ['Joob', 'python', 'bodd']
   >>> random.shuffle(p)
   >>> p
   ['bodd', 'Joob', 'python']
   

   • 1
   • 2
   • 3
   • 4
   • 5
   • 6
   • 7
   • 8

8. random.sample

   random.sample(sequeence,k): 从指定序列中随机获取指定长度的片段，但不会修改原有的序列

   >>> import random
   >>> list = [1, 2, 3, 4, 5, 6, 7]
   >>> a = random.sample(list,3)
   >>> a
   [5, 1, 4]
   >>> a = random.sample(list,4)
   >>> a
   [2, 4, 7, 5]
   >>> list
   [1, 2, 3, 4, 5, 6, 7]
   

   • 1
   • 2
   • 3
   • 4
   • 5
   • 6
   • 7
   • 8
   • 9
   • 10