How to generate multiple 9 digit random numbers in one go and add a prefix number to them in python

Question

I want to generate multiple ( n number) 9 digit random numbers in one go in python and then add a prefix digit (say 1) to each of these numbers (making them 10 digit numbers) and then write them to a file? I know how to generate a single random number using:

import random
random.randint(100000000,999999999)

But how do I generate multiple numbers in one go and then a add predetermined prefix digit to each of them before writing them to a file?

Answer 1

Here I am doing for 10 numbers which are generated randomly , do it for how many numbers you want,

import random
for i in range (10):
    ang = random.randrange(100000000,999999999)
    print int("1"+str(ang))

Answer 2

You can do something like this:

import random
file = open("output.txt", "ab")

def generate_random(n):
    for i in range(n):
        number = random.randint(1100000000, 1999999999)    #No need to ppend 1 after generating number.
        file.write(str(number)+"\n")

generate_random(10)

So the output file looks like this:

1972697009
1588689225
1801344328
1405227028
1801903655
1868723502
1358721529
1394641572
1104858492
1694223145

Hope this helps.

Answer 3

You sound like you might be interested in random.sample . However, sample explicitly only produces unique values unless there are duplicate values in the population. This may or may not be what you want.

With sample you could do something like:

import random

prefix = 1 # or something like "#1" if that's what you want
digits = 9
num_samples = 9
values = random.sample(range(10**digits), num_samples)
strings = ["{}{:0{}}".format(prefix, v, digits) for v in values]

with open("yourfile.txt", "w") as f:
    print(*strings, sep="\n", file=f)

Answer 4

Just select a random sample of 9 numbers in the final 10-digit range. This also ensures that each number in the resulting list will be unique.

import random

numbers = xrange(1000000000, 2000000000)
sample = random.sample(numbers, 9)
print(sample)

Output:

[1705109241, 1634244584, 1769529233, 1858322249, 1266131804, 1019067146,
 1781176897, 1274126811, 1216604448]