[Tutor] Built In Functions

[Rafael Knuth]

Hej there,

> I use any() and all() frequently. For example, suppose you have a
> function that takes a list of numbers, and they are all supposed to be
> positive.
>
> def calculate_values(numbers):
>     if all(number > 0 for number in numbers):
>         # do the calculation
>     else:
>         raise ValueError("negative or zero number found")
>
> That could be re-written as:
>
> def calculate_values(numbers):
>     if any(number <= 0 for number in numbers):
>         raise ValueError("negative or zero number found")
>     else:
>         # do the calculation

Got it. I played with the examples above, I wrote wrote two functions
and they work nicely.
I understand now why it makes sense to use all() and any():

def check_values(a, b):
    if all(number >= 0 for number in range(a, b)):
        return True
    else:
        raise ValueError("negative number")

And:

def check_values(a, b):
    if any(number >= 0 for number in range(a, b)):
        return True
    else:
        raise ValueError("negative number")

But what if I have to check multiple values within one function? I am
able to get the task done with a plain vanilla if statement. In the
exemplary function below the user is expected to enter only positive
numbers and in case he provides a negative number, a ValueError is
raised:

def PositiveCalculator(a, b):
    if a > 0 and b > 0:
        return a + b
    else:
        raise ValueError("negative number")

In this function one negative number is tolerated:

def PositiveCalculator(a, b):
    if a > 0 or b > 0:
        return a + b
    else:
        raise ValueError("negative number")

How would I have to modify these two functions if I wanted to use the
all( ) or any() function respectively?

Thanks in advance!

All the best,

Raf