random module
Get to know random module
The random module contains functions that return random numbers, which can be useful for simulations or any program that generates random output.
The following table has some important functions in the random module.
| Function | Description |
|---|---|
| random() | Returns a random real number n such that 0 <= n < 1 |
| getrandbits(n) | Returns n random bits, in the form of a long integer |
| uniform(a, b) | Returns a random real number n such that a <= n < b |
| randrange([start], stop, [step]) | Returns a random number from range(start, stop, step) |
| choice(seq) | Returns a random element from the sequence seq |
| shuffle(seq[, random]) | Shuffles the sequence seq in place |
| sample(seq, n) | Chooses n random, unique elements from the sequence seq |
random.randrange
The function random.randrange is the standard function for generating a random integer
in the range.
For example, to get a random number in the range from 1 to 10 (inclusive),
you would use randrange(1,11)
(or, alternatively, randrange(10)+1), and if
you want a random odd positive integer lower than 20, you
would use randrange(1,20,2).
import random# from w w w . ja v a 2 s . c om
# generate random numbers 1 - 6
die1 = random.randrange(6) + 1
die2 = random.randrange(6) + 1
print die1
print die2
The code above generates the following result.
Random integers produced by randrange.
import random
for i in range( 1, 21 ):
print ( random.randrange( 1, 7 ) )
The code above generates the following result.
Roll a six-sided die 6000 times.
import random# from w w w.j av a2 s . c o m
frequency1 = 0
frequency2 = 0
frequency3 = 0
frequency4 = 0
frequency5 = 0
frequency6 = 0
for roll in range( 1, 6001 ): # 6000 die rolls
face = random.randrange( 1, 7 )
if face == 1: # frequency counted
frequency1 += 1
elif face == 2:
frequency2 += 1
elif face == 3:
frequency3 += 1
elif face == 4:
frequency4 += 1
elif face == 5:
frequency5 += 1
elif face == 6:
frequency6 += 1
else: # simple error handling
print "should never get here!"
print "Face %13s" % "Frequency"
print " 1 %13d" % frequency1
print " 2 %13d" % frequency2
print " 3 %13d" % frequency3
print " 4 %13d" % frequency4
print " 5 %13d" % frequency5
print " 6 %13d" % frequency6
The code above generates the following result.
Random int value
import random# w w w. ja v a 2 s . co m
random.random()
random.random()
print random.randint(1, 10)
print random.randint(1, 10)
The code above generates the following result.
Random float
import random
print random.random() # random float
The code above generates the following result.
Random string value
import random
print random.choice(['apple', 'pear', 'banana'])
The code above generates the following result.
Sampling without replacement
import random
print random.sample(xrange(100), 10) # sampling without replacement
The code above generates the following result.
