Assignments

[Note: this webpage last modified Monday, 10-Dec-2012 19:44:57 EST]

Software Environment/Installation/Login

Installing Python.   We will be using the Python software that can be downloaded from http://python.org/download/. You should download and install the latest 2.7.x version (currently version 2.7.3 as I write this webpage). We will also use some add-ons later in the semester; I will provide links to those when they are needed.

It is absolutely required that you have access to a working computer with Python installed that you have access to outside of class time. The biggest factor in your success in the course is how much time you spend programming outside of class.

Installing WinSCP or FileZilla.   To turn in homework assignments, you will need to install a program called an sftp client. Two that are free that I recommend are FileZilla or WinSCP.

cs151xx login to CS server.   You will turn your assignments in by uploading your finished assignment to the Computer Science server. I have administrator access to this server and can easily grade your homeworks once they are on the server. You will receive an email giving you a username and login to the CS server. The username will be cs151xx, where xx is just a number - so the "first" student in the class will get cs15100 as their login, etc. You use either FileZilla or WinSCP with your CS login/password to upload your homework files to the CS server. This is demonstrated in the first lecture. That lecture has been recorded and is available to view in blackboard - go to blackboard for this course, and click "Tegrity Classes".

Project

Basic idea: create a "significant" program that uses most of the key programming features we have learned in class. You can choose what the program does, but your choice must be approved by Jeff.

Rules:

Homework Assignments

The homework assignments are posted in the in class code. hw1.py contains the first homework assignment, hw2.py is the second homework assignment, etc. I will announce in class and/or by email when a new assignment has been posted. Each homework assignment will list the date the assignment is due. Late assignments will not receive any credit; I will grade them just so you know how you did.

To complete a homework assignment, (1) download the assignment from the in class code, (2) make changes to the file provided to complete the assignement, (3) upload your completed assignment to the CS server before the due date. To download the file, you should browse to the in class code on the course website, right-click, and choose "Save as" or "Save target as" (depending on your browser) to save the file to your computer. For each assignment, you must download the template file to use as a starting point, make changes to this file, and then upload this file. If you do not turn in your homework in this way, I will take off points! DO NOT copy/paste into a word document, or send an email with your assignment. DO NOT change the name of the homework file - keep the name exactly the same as on the class website.

Here is a rough idea of my plans for the first few assignments.

Final Exam

Exam topics and format

Format is the same as previous exams. Remember that the exam will count either as 15% of the total grade or as 35% (replacing the previous two exams) - whichever is better for you. The exam is cumulative because that is just the nature of programming and computer science. But the focus is on the material in the second half of the course - loops, functions, lists, dictionaries, tuples, files. The breakdown of types of questions are as follows.

You can use all the previous test questions and sample test questions as practice for this test. Here are a few extra sample questions off the top of my head. You should also review the examples we did in class and from the book. I always base some questions off of those.

  1. Give Code. Write a function that reads in a list of numbers from a text file, with one number on each line, and prints how many of the numbers are even.

  2. Give Code. Write a function that asks the user for their first name, last name, major, and password. This information should be put into a dictionary, and the dictionary and the dictionary saved into a text file using pickle.

  3. Give Code. Write a function that asks a user to type some text. The code then tells the user how many letters they typed (do not include spaces) and also tells them how many words they typed.

  4. Give Code. Write a function that takes as input a list where each item of the list is a tuple with a name and a number that is their grade. For example the input list could be [('paula', 79), ('jerry', 95), ('susan', 90)]. The function should return the name of the person with the highest grade.

  5. Fix Logical Errors. The following is supposed to be a function that takes as parameter the name of a file. It reads all the words in the file, and keeps a count of how many times each word appears. A dictionary with these counts and should be returned. There are two logical errors to find. 

    def commonWords(fileName):
    f = open(fileName, 'r')
    s = f.read()
    f.close()

    d = {}
    s = ''

    word = ''
    for letter in s:
        if letter.isalpha():
            word += letter.lower()
        else:
            if word != '':
                if word in d:
                    d[word] += 1
                else:
                    d[word] = 1
            word = ''

  6. Fix Logical Errors. The following is supposed to count the number of vowels in a string. There are two logical errors to find and fix. 

    def countVowels(s):
    count = 0
    i = len(s)
    while i < len(s):
        if s[i].lower() == 'a' or 'e' or 'i' or 'o' or 'u':
            count += 1
        i += 1
    return count
print countVowels('Hello there.  This is awesome.')

  7. Be the computer. 

    def binary(n):
    if n==0: print '0'
    elif n==1: print '1'
    else: 
        print str(n%2)
        binary(n/2)
binary(9)

  8. Be the computer. 

    def addThem(n,m):
    total = 0
    for i in range(n,m+1):
        total = total + i
    return total
print addThem(5,10)

  9. What is printed. 

    import pickle
def saveData(data, fileName):
    s = pickle.dumps(data)
    f = open(fileName, 'w')
    f.write(s)
    f.close()        
def loadData(fileName):
    f = open(fileName, 'r')
    s = f.read()
    f.close()
    return pickle.loads(s)

x = range(0, 10)
y = ['hi', 'the', 'it']
z = {'first': x, 'second': y}
saveData(z, 'data.txt')
w = loadData('data.txt')
print str(w['second'][0])

  10. What is printed. 

    myMap = '''
******
*    *
* *  *
* ** *
*x*G *
****'''
myMap = myMap[1:].split('\n')
for i in range(0, len(myMap)):
    myMap = list(myMap[i])
print myMap[4][3]

  11. Fix syntax errors. The following is supposed to check a person's password. It reads the password from a file called 'password.txt', and should keep asking as long as the person enters the wrong thing. There are at least 3 syntax errors to fix. 

    def checkPassword():
    f = open('password.txt',r)
    correct = f.read()
    f.close()

    attempt = raw_input('Enter password. ')
    while attempt != correct:
        print 'Wrong.  Try again'
        attempt == rawinput('Enter password. ')

  12. Fix syntax errors. The following is supposed to ask the user a math fact and return True if they got it wrong, and False if they got it right. There are at least 3 syntax/runtime errors to fix. 

    import random
def challengeFailed():
    x = randint(-100, 100)
    y = randint(-100, 100)
    answer = raw_input('What is ' + x + ' + ' + str(y) + ' ?')
    try:
        if x + y == int(answer):
            return false
    except Exception, e:
        return true
    return true

  13. True or False. Binary search is much slower than linear search when searching through a sorted list of numbers, especially when the list gets very long.

  14. True or False. Selection sort should always be used rather than merge sort, because it is much simpler code.

Second Exam

Exam topics and format

Format will be simlar to the first exam. The only difference is that the breakdown of types of questions will be slightly different.

The exam will be commulative, so everything you should have known from the first test you should still know. This means you can take the first exam and first sample exam as practice questions for this exam too.

New material that was not on the first test includes for loops, turtles, and lists/dictionaries/tuples.

Advice

I have taken examples from our in-class examples, the homeworks, and the textbook - both for the sample exam and for the real exam. You should study all of those - in-class code examples, homeworks, and textbook exmaples.

Sample Exam

  1. T/F. A function must always return a value. A function without a return statement is an error.

  2. T/F. A while loop is used to run the same code over and over again until some condition is True.

  3. T/F. The following code prints the value 3. 

    def fun(x):
  return x * 3
print fun('1')

  4. T/F. len(L) is 10 when the code is done. 

    L = ['1', 0, (1, 2)]
for i in range(0, 6):
  L.append(i*2)

  5. T/F. If you have a dictionary in variable d, then you can add an entry with key 'k' and value 2 as follows. 

    d.append('k':2)

  6. What is printed. 

    logins = '''login password
bhiggins 12345
nbonaparte asdf
estewart jkl'''
logins = logins.split('\n')
print logins[1]

  7. What is printed. Draw what the turtle draws. 

    from turtle import *
resetscreen()
for i in range(0, 3):
  penup()
  setx(i*150 - 150)
  pendown()
  for j in range(0, 4):
    forward(100)
    right(90)
mainloop()

  8. Be the computer. 

    def encrypt(msg, password):
  msg = msg.lower()
  E = ''
  for letter in msg:
      num = ord(letter) + password - ord('a')
      num = num % 26
      E = E + chr(num + ord('a'))
  return E
print encrypt('dad', 5)

  9. Be the computer. 

    def moreStuff(L):
  for val in L:
    L.append(val)
stuff = ['apple', 'orange', 'banana']
moreStuff

  10. Fix the syntax/runtime errors. The function is supposed to determine if the word is a palindrome (same front-to-back as back-to-front, like mom). There are 4 errors, fix at least 2 of them. 

    def is_palindrome(word):
    i == 0
    j = length(word)-1

    while i<j:
        if word[i] != word(j):
            return False
        i = i+1
        j = j-1

    return true
print is_palindrome('retreiver')

  11. Fix the syntax/runtime errors. The function is supposed to take a number and look up who got that grade. There are 4 errors, fix at least 2 of them. 

    def reverse_lookup(d, v):
    for k in d:
        if d(k) == v
            return k
    return none
D = ['gigi':100, 'wanda',:99, 'jose':98, 'luis':97]
print reverse_lookup(D, 98)

  12. Fix the logical errors. In the example below, the function should return 'file.txt'. There are 2 logical errors, fix them both. 

    def parseFilename(s, divider):
  index = s.rfind(divider)
  return s[index:]
print parseFilename('/', 'c:/users/blah/file.txt')

  13. Fix the logical errors. The function is supposed to find the median of a list of numbers. There are 2 logical errors, fix them both. 

    def median(L):
  # if list is sorted, find the middle index.
  if len(L) == 0: return None
  elif len(L) == 1: return L[0]
  elif len(L) % 2 == 1: return L[len(L)/2 - 1]
  else: return (L[len(L)/2-1]+L[len(L)/2])/2.0
  L.sort()

L = [5, 6, 0, 4, -19, 20, 1.5]
print 'Median is ' + str(median(L))

  14. Give code. Given a dictionary playerData, determine if the dictionary has a key for 'points', and if so then add one to the points and print the value.

  15. Give code. Create a function called numAs that has one parameter called grades. grades will be a list of numbers. The function should return how many numbers are A grades ( >= 90).

First Exam

Exam topics

The exam covers everything we have done up until now. The questions on strings will be limited to more basic questions since we have not had as much time with those. See the schedule for the list of topics we have covered.

Exam format

The exam will be in class, on paper, no computer/calculator/etc. You can bring one sheet of paper with anything you want on it (front and back, handwritten or computer printout). The exam will consist of the following, for a total of 39 points.

For T/F, you must give a short (1 sentence is normally enough) explanation for why the answer is T or F. For the "What is printed", show some work or give a 1 sentence explanation for why you give the answer you give. For "Be the computer", keep track of every variable that is created and all of its values as the program is run.

Advice

I have taken examples from our in-class examples, the homeworks, and the textbook - both for the sample exam and for the real exam. You should study all of those - in-class code examples, homeworks, and textbook exmaples.

Sample Exam

Here is a sample exam with the types of questions that will be on the exam.

  1. T/F. Computer memory is much faster than hard drive.

  2. T/F. It is okay to have a variable with the name and.

  3. T/F. A function must always have a return statement in it, or it is an error.

  4. T/F. To convert a string to a number, use the str function.

  5. T/F. A while loop can be stopped by using the break statement.

  6. What is printed. 

    s = 'Monty Python'
print s[6:10]

  7. What is printed. 

    n = 0
while n < 5:
  print n
  n = n + 1

  8. What is printed. 

    x = 'a'
y = 'b'
if (x >= y) or (y > x) and not True:
  x = 'c'
elif x >= 'a':
  x = 'd'
else:
  x = 'e'
print x

  9. Be the computer. 

    x = 2
y = 3
x = y + x
z = y + x
y = z / 3
z = y ** 2
z = y % x

  10. Be the computer. 

    a = 5.0
x = 2.0
while True:
    print x
    y = (x + a/x) / 2
    if abs(x-y) < .01: break
    x = y

  11. Be the computer. 

    def distance(x1, y1, x2, y2):
    dx = x2 - x1
    dy = y2 - y1
    dsquared = dx**2 + dy**2
    result = math.sqrt(dsquared)
    return result
def area(radius):
    temp = math.pi * radius**2
    return temp
def circle_area(xc, yc, xp, yp):
    radius = distance(xc, yc, xp, yp)
    result = area(radius)
    return result
A = circle_area(0,0,0,1)
print A

  12. Fix the syntax/runtime errors. The following function is supposed to print a triangle of *'s. There are 4 syntax/runtime errors. Find and fix 2 of the errors. 

    def triangle(num):
s = '"
    while num > 0:
        s = s + '*'
        print s.
        num = num - 1
Triangle(10)

  13. Fix the syntax/runtime errors. The following function is supposed to compute a grading scall and return the correct letter grade. There are 4 syntax/runtime errors. Find and fix 2 of the errors. 

    Def letterGrade[num]
    # based on num, decide if they get an A, B, C, D, F, and return
    # the correct letter.  Assume 90-100 is A, 80-89.9999 is a B, etc.
    if num < 60: return F
    elif num < 70: return 'D'
    elif num < 80: return 'C'
    elif num < 90: return 'B'
    else: return 'A'

print letterGrade(99)

  14. Give code. Give code for a function called rps that takes two arguments/parameters. The arguments will be strings having one of the values "rock", "paper", or "scissors". Your function should print which player wins or if there is a tie.

  15. Give code. Give code that asks the user for 10 different numbers and outupts the average value. Use a while loop for full credit.