CODEWITHSUNDEEP
pythonrandom
user1393251
user1393251

Reputation: 199

How to generate negative random value in python

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?

Upvotes: 19

Views: 57436

Answers (11)

storenth
storenth

Reputation: 1225

Simplest solution:

random.randint(-999,-1)

Upvotes: 0

first
first

Reputation: 743

If you want to generate 2 random integers between 2 negative values than print(f"{-random.randint(1, 5)}") can also do the work.

Upvotes: 0

luca calabria
luca calabria

Reputation: 31

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]

Upvotes: 1

WoozyDragon
WoozyDragon

Reputation: 58

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!

Upvotes: 0

Sebastian Nielsen
Sebastian Nielsen

Reputation: 4219

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]

Upvotes: 5

Dylan Maulucci
Dylan Maulucci

Reputation: 1

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)

Upvotes: 0

San4ez
San4ez

Reputation: 8241

Use random.uniform(a, b)

>>> import random
>>> random.uniform(-1, 1)
0.4779007751444888
>>> random.uniform(-1, 1)
-0.10028581710574902

Upvotes: 36

MayTheSchwartzBeWithYou
MayTheSchwartzBeWithYou

Reputation: 1177

You can also do something like this

import random
random.choice([-1, 1])

Upvotes: 1

mata
mata

Reputation: 69052

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

Upvotes: 4

eumiro
eumiro

Reputation: 213005

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()

Upvotes: 7

BluePeppers
BluePeppers

Reputation: 1613

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].

Upvotes: 1

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