CS 1MD3 - Winter 2006 - Assignment #2

Generated for Student ID: 0561326

Due Date: Wednesday, February 8th

(You are responsible for verifying that your student number is correct!)

Part 1: Debugging

The following four functions are infested with bugs. Correct them by adding or changing a single line in each one. Clearly indicate your changes with comments. If you add a line, append the comment, "# added." If you change a line, append a comment to it containing the original, erroneous line. Solutions submitted without comments will not be marked.

1

def isPalindrome(aList):
	"""Returns True if the list reads the same backwards and forwards."""
	n = len(aList)
	cursor = 0
	while cursor < n:
		if (aList[cursor] != aList[-cursor-1]):
			return False
	cursor=cursor+1	
	return True

def mean(numberList):
	"""Returns the mean (i.e. average) value of the elements in the list"""
	n = len(numberList)
	if n == 0:
		return None
	theSum = 0
	i = 0
	while i <= n: 
		x = numberList[i]
		theSum = theSum + x
		i = i + 1
	return float(theSum) / float(n)

def deinterlaceEven(interlacedList):
	"""Returns a list consisting of only the even elements of the given list.
	For example, deinterlaceEven(['1', 'a', '2', 'b', '3', 'c']) returns [1,2,3]."""
	n = len(interlacedList)
	if n == 0:
		return None
	i = 0
	evenList = []
	while i < n:
		evnList.append(interlacedList[i])	
		i = i+2
	return evenList

def norm(aVector):
	"""Computes the Euclidian norm of the given vector in R^n.
	The Euclidean norm of x=(x1, x2, ..., xn) is defined as the square root of
	x1^2 + x2^2 + ... + xn^2."""
	n = len(aVector)
	if n <= 0:
		return None
	theNorm = 0
	i = 1-n
	while i <= 0:
		theNorm = theNorm + abs(aVector[i])**2
		i=i-1	
	return pow(theNorm, 0.5)

Part 2: Testing

Create automated tests for the following function using PyUnit. Your tests should ensure that the code produces the expected result in all cases.

def bubbleSort(aList):
	"""Sorts the given list using the (in)famous BubbleSort algorithm."""
	n = len(aList)
	i = 0
	while i < n-1:
		j = 0
		while j < n-i-1:
			if aList[j+1] < aList[j]:
				temp = aList[j]
				aList[j] = aList[j+1]
				aList[j+1] = temp
			j = j+1
		i = i+1