How can I generate random numbers and assign them to variables in python?

Question

Suppose I want the variables a_1, a_2, a_3, a_4 to be random numbers from the uniform distribution U(0,100). I could write

import random

a_1 = random.uniform(0,100) 
a_2 = random.uniform(0,100) 
a_3 = random.uniform(0,100)
a_4 = random.uniform(0,100)

But I was wondering if there is a more efficient way to do this. I tried the following,

import random

for i in range(4):
    a_i = random.uniform(1,100)
    print(a_i)

However, this did not work. For example, when I call a_1 later on, it says a_1 is not defined. How can I fix this?

It looks like you are trying to do something in the second piece of code like this: stackoverflow.com/questions/5036700/… If you only need the 4 variables just stick with the first piece of code. — Zack Tarr
– Zack Tarr, Commented Jan 11, 2018 at 19:54
If it weren't for the XY problem going on here, this would be an obvious duplicate. — Beefster
– Beefster, Commented Jan 11, 2018 at 19:59
Possible duplicate of How can you dynamically create variables via a while loop? — Beefster
– Beefster, Commented Jan 11, 2018 at 19:59
Possible duplicate of How do I create a variable number of variables? — Zero Piraeus
– Zero Piraeus, Commented Jan 12, 2018 at 1:08

Brian · Accepted Answer · 2018-01-11 19:57:42Z

4

Put the random values into a list and then access members by index:

>>> import random
>>> a = [random.uniform(1,100) for _ in range(4)]
>>> a
[71.4615087249735, 19.04308860149112, 40.278774122696014, 69.18947997939686]
>>> a[0]
71.4615087249735
>>> a[2]
40.278774122696014

Unless you have a really, really good reason, defining variables dynamically is kind of hard to justify.

answered Jan 11, 2018 at 19:57

Brian

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2 Comments

Artus Over a year ago

@Brain Thanks a lot, I never thought of making a list. However, what is wrong with the code that I wrote, why did it not work?

r.ook Over a year ago

@Artus because variables don't work dynamically like that. Your code only defined one variable a_i which has no relation to the i being iterated in the loop. Regardless of how many times you loop, you're still only reassigning to the one variable a_i. What you want is a list (essentially an array) like @Brian's answer, so you can loop through the list like a[i]

Camion · Accepted Answer · 2018-01-12 00:56:59Z

1

If you do not wish to use a list, you can use the unpack functionality

import random
up, down, strange, charm = [random.uniform(1,100) for _ in range(4)]

answered Jan 12, 2018 at 0:56

Camion

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4 Comments

Camion Over a year ago

Rofl... Took me a while to catch that one ;-)

Artus Over a year ago

@Camion thank you but I'm not sure I understand what up down strange charm means...

Camion Over a year ago

Those are just example of names for if you want named variables instead of position in a structure (those name are colors of quarks, just for fun).

Camion Over a year ago

The pack/unpack mechanism allows you to initialize multiple variables in one single operation : (a, b, c) = (1, 2, 3), but in this case the outside parenthesis are not required : a, b, c = 1, 2, 3

mkrieger1 · Accepted Answer · 2024-09-01 14:06:25Z

1

You can generate random integer within a range (or other iterable) like this:

import random

numberOf_intRequired = 4
random_int = random.sample(range(0, 100), numberOf_intRequired)

edited Sep 1, 2024 at 14:06

mkrieger1

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answered Jan 13, 2018 at 6:20

Dheeraj Teta

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