Function get_prime

maths/primelib.py:538–581

Gets the n-th prime number. input: positive integer 'n' >= 0 returns the n-th prime number, beginning at index 0 >>> get_prime(0) 2 >>> get_prime(8) 23 >>> get_prime(824) 6337 >>> get_prime(-1) Traceback (most recent call last): ... Assertion

(n)

def get_prime(n):
    """
    Gets the n-th prime number.
    input: positive integer 'n' >= 0
    returns the n-th prime number, beginning at index 0

    >>> get_prime(0)
    2
    >>> get_prime(8)
    23
    >>> get_prime(824)
    6337
    >>> get_prime(-1)
    Traceback (most recent call last):
        ...
    AssertionError: 'number' must been a positive int
    >>> get_prime("test")
    Traceback (most recent call last):
        ...
    AssertionError: 'number' must been a positive int
    """

    # precondition
    assert isinstance(n, int) and (n >= 0), "'number' must been a positive int"

    index = 0
    ans = 2  # this variable holds the answer

    while index < n:
        index += 1

        ans += 1  # counts to the next number

        # if ans not prime then
        # runs to the next prime number.
        while not is_prime(ans):
            ans += 1

    # precondition
    assert isinstance(ans, int) and is_prime(ans), (
        "'ans' must been a prime number and from type int"
    )

    return ans


# ---------------------------------------------------