Usage of Python random

Python's method of random inside is actually an object instantiated by random.

There are several commonly used in several Parties import random

Print(Random.Randint(1,10) ) # generates an integer random number from 1 to 10Print(Random.Random() ) # Generate random floating-point numbers from 0 to 1Print(Random.Uniform(1.1,5.4) ) # generates a random floating-point number between 1.1 and 5.4, and the interval may not be an integerPrint(Random.Choice(' Tomorrow ') ) # random selection of an element from a sequencePrint(Random.Randrange (1,100 2)     # Generate random integers from 1 to 100 with an interval of 2 a=[1 3,5,6 ,7] # to disrupt the order of elements in sequence a Span class= "PLN" >random. (a) print (a         

I'll see the source.
def randrange (self, start, Stop=none, Step=1, _int=int):

Self is the value you instantiate object start, stop is the key parameter, step interval 1 _int = Int (integer object)
    "" "Choose a random item from range (Start, stop[, step]).
　　　　　　

    This fixes the problem with Randint () which includes the
    Endpoint In Python, this is usually don't what want.

    """

    # This code was a bit messy to make it fast for the
    # Common case while still doing adequate error checking.
    Istart = _int (start)
Force Istart is an integer
    If Istart! = Start:
　　Determine if start is not an integer
        Raise ValueError ("Non-integer Arg 1 for Randrange ()")
Parameter error

)
If stop is None:
whether the keyword argument for the end value of the interpretation is none
If Istart > 0:
 　　　　　　 determine if the start value is greater than 0
Return Self._randbelow (Istart)
 　　　　　　　　 call _randbelow method to pass in and out, is probably the maximum range of judging the starting value
Raise ValueError ("Empty range for Randrange ()")
 　　　　　 triggering a value that cannot be null error
# Stop argument supplied.
Istop = _int (stop)

If istop! = Stop:
Raise ValueError ("Non-integer Stop for Randrange ()")
 　　 range values for loops
width = Istop-istart

If step = = 1 and width > 0:
return Istart + self._randbelow (width)
If step = = 1:
Raise ValueError ("Empty range for Randrange () (%d,%d,%d)"% (Istart, istop, width))

# non-unit Step argument supplied.
Istep = _int (step)
If istep! = Step:
Raise ValueError ("Non-integer Step for Randrange ()")
If Istep > 0:
n = (width + istep-1)//Istep
 　　　　　 N (should be the number of random loops)For example (1,10) Wdith = 10-1 + istep =2//2 n =5
So the ordered set is 5 "1,3,5,7,9"
 
Elif Istep < 0:
n = (width + istep + 1)//Istep
Else
Raise ValueError ("Zero Step for Randrange ()")

If n <= 0:
Raise ValueError ("Empty range for Randrange ()")

return Istart + istep*self._randbelow (n)
Looked down the source code can not see

def choice (self, seq):
    "" "Choose a random element from a non-empty sequence." ""
Select a random element from a set that has a virtual collection, what is the "string, list, and ancestor" of the ordered collection in Python
Both the dictionary and the collection are invalid

    Try
        i = Self._randbelow (len (seq))
    Except ValueError:
        Raise Indexerror (' cannot choose from an empty sequence ')
    return Seq[i]

def randint (self, A, b):
    "" "Return random integer in range [A, b], including both end points.
    """

    Return Self.randrange (A, b+1) here's the point. I'm not going to say anything.

PYTHON Random Module (get random number) common methods and usage examples

Random.random
Random.random () is used to generate a random number of 0 to 1 points: 0 <= N < 1.0

Random.uniform
Random.uniform (A, b), used to generate a random number of characters in a specified range, two parameters one of which is the upper bound, and the other is the lower limit. If a > B, the generated random number n:a <= n <= B. If a <b, then B <= N <= a

The code is as follows:
Print Random.uniform (10, 20)
Print Random.uniform (20, 10)
# 18.7356606526
# 12.5798298022

Random.randint
Random.randint (A, b), used to generate an integer within a specified range. Where parameter A is the lower limit, parameter B is the upper limit, the generated random number n:a <= n <= B

The code is as follows:
Print Random.randint (12, 20) # generated random number N:12 <= n <= 20
Print Random.randint (20, 20) # The result is always 20
# Print Random.randint (20, 10) # The statement is wrong. Lower limit must be less than upper limit

Random.randrange
Random.randrange ([start], stop[, step]), from within the specified range, gets a random number in the collection incremented by the specified cardinality. such as: Random.randrange (10, 100, 2), the result is equivalent from [10, 12, 14, 16, ... 96, 98] gets a random number in the sequence. Random.randrange (10, 100, 2) equivalent to Random.choice (range (10, 100, 2) on the result

Random.choice
Random.choice gets a random element from the sequence. Its function prototype is: Random.choice (sequence). The parameter sequence represents an ordered type. Here's a note: sequence is not a specific type in Python, but a series of types. list, tuple, string all belong to sequence. For sequence, you can view the Python manual data Model chapter. Here are some examples of using choice:

The code is as follows:
Print Random.choice ("Learning python")
Print Random.choice (["Jgood", "is", "a", "handsome", "boy"])
Print Random.choice (("Tuple", "List", "Dict")

Random.shuffle
Random.shuffle (x[, Random]), which is used to disrupt elements in a list. Such as:

The code is as follows:
p = [' Python ', ' is ', ' powerful ', ' simple ', ' and so ' on ... ']
Random.shuffle (P)
Print P
# [' Powerful ', ' simple ', ' was ', ' Python ', ' and so on ... ']

Random.sample
Random.sample (sequence, k), randomly fetching fragments of the specified length from the specified sequence. The sample function does not modify the original sequence

The code is as follows:
list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Slice = random.sample (list, 5) # randomly fetches 5 elements from the list, returning as a fragment
Print Slice
Print List # The original sequence has not changed

Random integers:

The code is as follows:>>> import random
>>> Random.randint (0,99)
# 21

Randomly select even numbers between 0 and 100:

The code is as follows:>>> import random
>>> random.randrange (0, 101, 2)
# 42

Random floating point number:

The code is as follows:>>> import random
>>> Random.random ()
0.85415370477785668
>>> random.uniform (1, 10)
# 5.4221167969800881

Random characters:

The code is as follows:>>> import random
>>> random.choice (' abcdefg&#%^*f ')
# ' d '

Select a specific number of characters in more than one character:

The code is as follows:>>> import random
Random.sample (' Abcdefghij ', 3)
# [' A ', ' d ', ' B ']

Select a specific number of characters to form a new string in multiple characters:

The code is as follows:>>> import random
>>> Import String
>>> String.Join (Random.sample ([' A ', ' B ', ' C ', ' d ', ' e ', ' f ', ' g ', ' h ', ' I ', ' J '], 3)). Replace ("", "" ")
# ' FIH '

Randomly pick a string:

The code is as follows:>>> import random
>>> random.choice ([' Apple ', ' pear ', ' peach ', ' orange ', ' Lemon '])
# ' Lemon '

Shuffle:

The code is as follows:>>> import random
>>> items = [1, 2, 3, 4, 5, 6]
>>> random.shuffle (items)
>>> Items
# [3, 2, 5, 6, 4, 1]

Usage of Python random