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Python Python Basics (2015) Logic in Python Fully Functional

Qui Le
Qui Le
10,235 Points
Posted by Qui Le
Qui Le
10,235 Points

Small Challenge from Teacher's Note

Hi Kenneth,

I think about how to make function even() simpler. If num is even, num % 2 will be 0. So, my solution is to use keyword not to negate the condition of whether num % 2. I return True because of the negation of the condition. I return False at the end of function. I don't need to have else statement.

Is that how I improve the function?

2 Answers

Gyorgy Andorka
Gyorgy Andorka
13,811 Points
Gyorgy Andorka
Gyorgy Andorka
13,811 Points

Inverting the conditions is irrelevant, the two are equivalent:

def even1(num):
    if num % 2 == 0:
        return True
    return False

def even2(num):
    if num % 2 != 0:  #  equivalent to if not (num % 2 == 0)
        return False
    return True

Leaving out the else branch is a valid optimization (in terms of length, at least), but I suppose Kenneth was thinking about an even more concise way :)

def even(num):
    return num % 2 == 0

Here's the trick: since num % 2 == 0 is an equality check and thus a boolean expression (an expression which evaluates to True or False), we can simply return this expression. If the program encounters an expression like this, it first computes the value of it, then do whatever else it should do with it, in this case return (I see return <something> on the next line -> let's figure out what that something is -> that something's value is True -> so I should return True).

Qui Le
Qui Le
10,235 Points
Qui Le
Qui Le
10,235 Points

Wow! Your response to the challenge is very concise. It is indeed simple and beautiful. Thank you for your insight!