CODEWITHSUNDEEP
pythonpython-2.7
Rockybilly
Rockybilly

Reputation: 4510

Incrementing a number based on its sign

In a project of mine, I have to implement a function that adds or subtracts 1 based on the number's sign. Something like this,

def func(num):
    if num > 0:
        return num + 1
    if num < 0:
        return num - 1

But this seems like a unnecessarily long implementation for such a simple behavior. Is there an easier way to accomplish this. Maybe a one-liner ?

Upvotes: 2

Views: 83

Answers (4)

ghui
ghui

Reputation: 166

def func(num):
    if (num == 1):
        return 2
    elif (num == -1):
        return -2
    elif (num > 1):
        return 1 + func(num-1)
    else: 
        return -1 + func(num+1)

Can add an extra if check if 0 is an input to check for.

Upvotes: 0

Bink
Bink

Reputation: 91

Could use lambda to write a one line function.

a = lambda x: x+1 if x < 0 else x-1

Call it by doing this:

print(a(5)) # This would return 4 as the value.

Upvotes: 1

tom10
tom10

Reputation: 69192

return  num + math.copysign(1, num)

Upvotes: 4

Nicolas Heimann
Nicolas Heimann

Reputation: 2581

You can use math module here:

>>> from math import copysign
>>> a = -1
>>> a += copysign(1,a)
>>> a
-2.0
>>> a = 3
>>> a += copysign(1,a)
>>> a
4.0

Numpy also provides a sign function

import numpy as np
a = 5
a += np.sign(a)
6

Upvotes: 3

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