Computes the inner product of two arrays (lists). The lists must be the same length as each other. The inner product is the sum of the products of elements with matching indices from each array.

U11_Ex07_InnerProd.py

# U11_Ex07_InnerProd.py
#
#  Author: Bill Montana
#  Course: Coding for OOP
# Section: A3
#    Date: 20 Mar 2018
#     IDE: PyCharm Community Edition
#
# Assignment Info
#   Exercise: 7
#     Source: Python Programming
#    Chapter: 11
#
# Program Description
#   Computes the inner product of two arrays (lists). The lists must be the same
#   length as each other. The inner product is the sum of the products of elements
#   with matching indices from each array.
#
# Algorithm (pseudocode)
#   ensure lists are same-length; throw an error if not
#   initialize an accumulator to zero
#   iterate over the length of the lists
#       sum the products of elements with matching indices to the accumulator
#   return the sum


def innerProd(list1, list2):
    """
    Computes the inner product of list1 and list2
    :param list1: list -> first list (elements are either int or float)
    :param list2: list -> second list (elements are either int or float)
    :return: int or float -> inner product
    """
    try:
        a = list2[len(list1)-1]
        b = list1[len(list2)-1]
    except IndexError:
        return "Lists must be of same length."
#        quit(1)

    innerProd = 0
    for i in range(len(list1)):
        innerProd += list1[i] * list2[i]
    return innerProd


if __name__ == '__main__':
    print(innerProd([1,2], [4,5,6]))

RESULTS:
========
innerProd([1,2,3], [4,5,6])   -->                              32 |                              32 | [ Pass ]
innerProd([1,2,3], [4,5])     -->   Lists must be of same length. |   Lists must be of same length. | [ Pass ]
innerProd([1,2], [4,5,6])     -->   Lists must be of same length. |   Lists must be of same length. | [ Pass ]
innerProd([], [4,5,6])        -->   Lists must be of same length. |   Lists must be of same length. | [ Pass ]
innerProd([1,2,3], [])        -->   Lists must be of same length. |   Lists must be of same length. | [ Pass ]
========

Note that I made innerProd() return the string "Lists must be of same length." for testing purposes. My original code printed the message, then quit.