I am starting to learn python, I tried to generate random values by passing in a negative and positive number. Let say -1, 1.
How should I do this in python?
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11 Answers
>>> import random
>>> random.uniform(-1, 1)
0.4779007751444888
>>> random.uniform(-1, 1)
-0.10028581710574902
Comments
import random
def r(minimum, maximum):
return minimum + (maximum - minimum) * random.random()
print r(-1, 1)
EDIT: @San4ez's random.uniform(-1, 1) is the correct way. No need to reinvent the wheel…
Anyway, random.uniform() is coded as:
def uniform(self, a, b):
"Get a random number in the range [a, b) or [a, b] depending on rounding."
return a + (b-a) * self.random()
3 Comments
Li-aung Yip
def rand(): return 4 # Generated by fair dice roll. Guaranteed to be random.
user1393251
Thanks a lot.But cann't i do in this way.Where i want to pass the value as a argument while running the script. .#!/usr/bin/env python import sys , random r = sys.argv[1] y = sys.argv[2] print random.range(y,r)
eumiro
@user1393251 - you can do it this way (my
r method is called the same way the correct random.uniform is), just I am reinventing the wheel here… Take San4ez's answer.If you want a random whole number from a given interval
Example:
from random import randint
randint(-1,1) --> Randomly returns one of the following: -1, 0, 1
interval [-1, 1]
Comments
if you want integer in a specified range:
print random.randrange(-1, 2)
it uses the same convention as range, so the upper limit is not included.
random.uniform does something similar if you need float values, but it's not always clear if the upper limit is included or not
Comments
Most languages have a function that will return a random number in the range [0, 1], which you can then manipulate to suite the range you need. In python, the function is random.random. So for your range of [-1, 1], you can do this:
import random
random_number = random.random() * 2 - 1
By doubling the number we get a range of [0, 2], and by subtracting one from it, we get [-1, 1].
Comments
You can also do something like this
import random
random.choice([-1, 1])
answered Dec 17, 2013 at 22:25
MayTheSchwartzBeWithYou
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Comments
If you want n random values in a positive, negative or mixed range you can use random.sample(range(min,max), population).
The constraint is that distance(max-min) must be lower or equal than population value. In the example above you can generate at most 6 values
>> import random
>> random.sample(range(-3,3), 5)
[-2, -3, 2, -1, 1]
Comments
I find this to work on a list comprehension:
print([x for x in [random.randint(1, 11) * -1]])
or
#int range is n1 to n2
def make_negative(n1, n2):
print([x for x in [random.randint(n1, n2) * -1]])
make_negative(1,10)
Comments
I noticed this today.
random.randint(a, b)
where B > A or B is greater than A
So if we put -999 instead of A and 1 instead of B
It will give us a negative random integer or 0 and 1.
Also, this is a rule in Mathematics, bigger negative numbers are smaller in value than smaller negative numbers, like -999 < -1
This rule can be applied here!
Comments
If you want to generate 2 random integers between 2 negative values than print(f"{-random.randint(1, 5)}") can also do the work.
Comments
Simplest solution:
random.randint(-999,-1)
