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random[] function is used to generate random numbers in Python. Not actually random, rather this is used to generate pseudo-random numbers. That implies that these randomly generated numbers can be determined. random[] function generates numbers for some values. This value is also called seed value.
Syntax : random.seed[ l, version ]
Parameter :
- l : Any seed value used to produce a random number.
- version : A integer used to specify how to convert l in a integer.
Returns: A random value.
How Seed Function Works ?
Seed function is used to save the state of a random function, so that it can generate same random numbers on multiple executions of the code on the same machine or on different machines [for a specific seed value]. The seed value is the previous value number generated by the generator. For the first time when there is no previous value, it uses current system time.
Using random.seed[] function
Here we will see how we can generate the same random number every time with the same seed value.
Example 1:
Python3
import random
for i in range[5]:
random.seed[0]
print[random.randint[1, 1000]]
Output:
865 865 865 865 865
Example 2:
Python3
import random
random.seed[3]
print[random.randint[1, 1000]]
random.seed[3]
print[random.randint[1, 1000]]
print[random.randint[1, 1000]]
On executing the above code, the above two print statements will generate a response 244 but the third print statement gives an unpredictable response.
Uses of random.seed[]
- This is used in the generation of a pseudo-random encryption key. Encryption keys are an important part of computer security. These are the kind of secret keys which used to protect data from unauthorized access over the internet.
- It makes optimization of codes easy where random numbers are used for testing. The output of the code sometime depends on input. So the use of random numbers for testing algorithms can be complex. Also seed function is used to generate same random numbers again and again and simplifies algorithm testing process.
random.seed[a, version] in python is used to initialize the pseudo-random number generator [PRNG].
PRNG is algorithm that generates sequence of numbers approximating the properties of random numbers. These random numbers can be reproduced using the seed value. So, if you provide seed value, PRNG starts from an arbitrary starting state using a seed.
Argument a is the seed value. If the a value is None, then by default, current
system time is used.
and version is An integer specifying how to convert the a parameter into a integer. Default value is 2.
import random
random.seed[9001]
random.randint[1, 10] #this gives output of 1
# 1
If you want the same random number to be reproduced then provide the same seed again
random.seed[9001]
random.randint[1, 10] # this will give the same output of 1
# 1
If you don't provide the seed, then it generate different number and not 1 as before
random.randint[1, 10] # this gives 7 without providing seed
# 7
If you provide different seed than before, then it will give you a different random number
random.seed[9002]
random.randint[1, 10] # this gives you 5 not 1
# 5
So, in summary, if you want the same random number to be reproduced, provide the seed. Specifically, the same seed.