# =========================================================
# File: text_menu_example.py
# 2015-04-16 by A. Ortiz, ITESM CEM.
#
# This program demonstrates how to write a text-based
# application with a menu that contains several options
# for the user. Requires Python 3.
# =========================================================

#----------------------------------------------------------
def average(a):
    """Calculate the arithmetic mean of the list of numbers
       contained in a.
    """
    return sum(a) / len(a)

#----------------------------------------------------------    
def compute_average():
    """User interface for computing the average of some
       numbers typed by the user. Prints the average
       using two decimals of precision after the point.
    """
    print("\nCOMPUTE AVERAGE")
    print("---------------")
    n = int(input("How many numbers? "))
    a = []
    for i in range(n):
        x = float(input("Give me number: "))
        a.append(x)
    print("Average is:", round(average(a), 2))

#----------------------------------------------------------
def fact(n):
    """Calculate the factorial of n.
       n! = (1)(2)(3)...(n - 1)(n)
    """
    a = 1
    for i in range(1, n + 1):
        a *= i
    return a

#----------------------------------------------------------
def compute_factorial():
    """User interface for computing the factorial
       of a number typed by the user.
    """
    print("\nCOMPUTE FACTORIAL")
    print("-----------------")
    x = int(input("Give me number: "))
    print("Factorial of", x, "is", fact(x))

#----------------------------------------------------------
def main():
    """Main program menu to select the user options.
    """
    while True:
        print("\nMENU")
        print("====")
        print("1. Compute the average of numbers")
        print("2. Compute a factorial")
        print("3. Quit")
        option = int(input("Choose an option: "))
        if option == 1:
            compute_average()
        elif option == 2:
            compute_factorial()
        elif option == 3:
            break
    
main() # Start program.