CSE 1310 - Summer 2013 - Lectures

• Lecture 1: Tue 07/09 - Introduction
  • Book reading: Chapter 1.
  • Slides: Introduction. PDF, PPT.
  • Slides: A first program. PDF, PPT.
    • Code: circles_1.py. A program computing the circumference and area of a circle. Here, the value of the radius of the circle is hardcoded into the program. The program must be changed every time we want to change the value of the radius.
    • Code: circles.py. A program computing the circumference and area of a circle. Here, the value of the radius of the circle is entered by the user when we run program. This way, the program does not need to be changed every time we want to change the value of the radius.
    • Code: circles_bad_style.py. An alternative version of circles.py, that runs exactly the same way, but uses poor programming style.
    • Code: fahrenheit_to_celsius.py. A program that converts Fahrenheit temperatures to Celsius.

• Lecture 2: Wed 07/10 - Program State, Expressions, Assignments, Types
  • Book reading: Chapter 1.
  • Slides: Program State and Program Execution, version 1. PDF, PPT.
  • Slides: Expressions, statements, variables, assignments, types. PDF, PPT.
    • Code: ex20120123a.py (author: Darin Brezeale). Creating int, float, and string variables.
    • Code: ex20120123b.py (author: Darin Brezeale). An example of type conversions.

• Lecture 3: Thu 07/11 - If statements
  • Book reading: Chapter 2.
  • Slides: If statements. PDF, PPT.
    • Code: ex20120123c.py (author: Darin Brezeale). An example of using if-else.
    • Code: ex20120123d.py (author: Darin Brezeale). An example of using if-elif statements.
    • Code: example-leapyear.py, example-leapyear-shorter.py (author: Darin Brezeale). Calculating if a year is a leap year. First example uses nested if statements. Second example uses a logical operator to combine cases.
    • Code: ex20120125a.py (author: Darin Brezeale). Categorizing the age of a person. Uses if-elif-else
    • Code: ex20120125b.py (author: Darin Brezeale). Guessing what animal you are, by asking two questions. Uses nested if-else statements
    • Code: if-indentation.py. An example showing the importance of indentation in if statements.

• Lecture 4: Mon 07/15 - Loops
  • Book reading: Chapter 2.
  • Slides: Loops. PDF, PPT.
    • Code: summing_to_N_for_loop.py Computing the sum of all numbers 0 and N. Uses a for loop.
    • Code: summing_to_N_while_loop.py Computing the sum of all numbers 0 and N. Uses a while loop.
    • Code: summing_to_N_bad_indent.py Computing the sum of all numbers 0 and N. Uses a while loop. Deliberately uses bad indentation at last line, to show the difference that indentation makes.
    • Code: ex20120125c.py (author: Darin Brezeale). Computing the sum of all even numbers between 0 and 10. Uses a while loop.
    • Code: ex20120125d.py (author: Darin Brezeale). Counts integers in range of 20 to 100 that are divisible by 13 or 22. Uses a while loop.
    • Code: ex20120125e.py (author: Darin Brezeale). Prints integers in range of 20 to 1000 that are divisible by 13 or 22. Uses a while loop.
    • Code: number_guessing.py (author: Darin Brezeale). The computer picks a number, you try to guess it. Uses a while loop.
    • Code: number_guessing2.py (author: Darin Brezeale, modified by Vassilis Athitsos). Variation of previous program, the computer picks a number, you try to guess it. Uses a while True loop with a break statement.
    • Code: ex20120130b.py (author: Darin Brezeale). Finds and prints out divisors of an integer. Uses a while loop.
    • Code: ex20120130c.py (author: Darin Brezeale). Printing a multiplication table. An example of a nested while loop.
    • Code: square_root.py. Finding out the square root of a number. (Note: in python, a quick way to get square roots is to type number ** 0.5.) Uses a while loop

• Lecture 5: Tue 7/16 - Containers and Lists.
  • Book reading: Chapter 7.
  • Slides: Containers and Lists. PDF, PPT.
    • Code: months_no_lists.py A program showing the 12 months and their lengths, without using containers.
    • Code: months_lists1.py. A program showing the 12 months and their lengths, using lists.
    • Code: sort_n_numbers.py. A program asking the user to enter some numbers (the user specifies how many numbers), and then prints those numbers in ascending order.
    • Code: list_methods.py (author: Dr. Darin Brezeale). A program illustrating examples of various methods operating on lists.
    • Code: phone_numbers_1.py A program that first asks a user to enter some names and phone numbers, and then enters a loop, where the user enters a name and the program looks up and prints out the corresponding phone number.
    • Code: phone_numbers_2.py This is another variation of phone_numbers_1.py, that behaves mostly the same way. One difference is that here, when the user is done entering names and numbers, the program prints all phones and numbers that have been entered. Another difference is that this program prints a message when the name is not found in the catalog.
    • Code: phone_numbers_3.py This is another variation of phone_numbers_1.py, that behaves mostly the same way. One difference is that here the information is stored in a single list, as opposed to two lists. Another difference is that this program prints a message when the name is not found in the catalog.

• Lecture 6: Wed 7/17 - Strings.
  • Book reading: Chapter 4, except Sections 4.4, 4.7.
  • Slides: strings. PDF, PPT.
    • Code: change_third_letter.py This program gets a string from the user, and prints out a modified version, where the third letter of the original string is replaced with "A".
    • Code: change_third_letter_2.py Compared to change_third_letter.py, this is a different (but equivalent) implementation. The behavior is the same, but the code is much shorter.
    • Code: finding_substrings.py This program asks the user to enter two strings. Then, it finds all positions of the first string where the second string occurs, and it prints out those positions and the total number of such positions.
    • Code: erase_vowels.py This program asks the user to enter a string. Then, it constructs a new string, equal to what the user entered, except that all vowels have been erased.
    • Code: replace_vowels_with_a.py This program asks the user to enter a string. Then, it constructs a new string, equal to what the user entered, except that each vowel in the original string is replaced by the letter 'a'.

• Lecture 7: Thu 7/17 - First Midterm.

• Lecture 8: Mon 7/22 - Strings, continued.
  • See slides and code from previous lecture.

• Lecture 9: Tue 7/23 - Functions
  • Book reading: Chapter 6.
  • Slides: Functions. PDF, PPT.
    • Code: verify_integer0.py This program asks the user to enter a string, and checks whether that string represents an integer or not. This version IS NOT ENTIRELY CORRECT, as it has two limitations: 1). It does not allow minus signs. 2). It prints that the empty string (or a string consisting only of whitespace characters) is an integer.
    • Code: verify_integer1.py This program asks the user to enter a string, and checks whether that string represents an integer or not.
    • Code: using_verify_integer1.py This program asks the user to enter an integer, and prints out the result of multiplying that integer by 2. If the user does not enter an integer, the program prints an error message. No functions are used, thus the code for checking if a string is an integer or not has been copied-and-pasted from verify_integer1.py.
    • Code: using_verify_integer2.py This program asks the user to enter an integer, and prints out the result of multiplying that integer by 2. If the user does not enter an integer, the program keeps asking the user to re-enter. No functions are used, thus the code for checking if a string is an integer or not has been copied-and-pasted from verify_integer1.py.
    • Code: number_check.py A separate file that defines two functions: Function check_integer(my_string), checks if my_string represents an integer or not. Function get_integer(message), gets an integer from the user, and asks the user again and again if the user does not enter a valid integer. These functions can now be imported and used by any piece of Python code.
    • Code: using_number_check1.py This program asks the user to enter an integer, and prints out the result of multiplying that integer by 2. If the user does not enter an integer, the program prints an error message. This version uses function check_integer.
    • Code: using_number_check2.py This program asks the user to enter an integer, and prints out the result of multiplying that integer by 2. If the user does not enter an integer, the program keeps asking the user to re-enter. This version uses function get_integer.

• Lecture 10: Wed 7/24 - Functions, continued.
  • See slides and code from previous lecture.
    • Additional code: summing_to_N_no_functions.py This program asks the user to enter a number N, and prints out the sum of integers from 0 to N. This is a revised version of summing_to_N_for_loop.py posted for a previous lecture, that uses the code from verify_integer2.py to ensure that the user enters a valid integer. However, no functions are used, and the resulting code is ugly.
    • Code: summing_to_N_with_functions_1.py A rewrite of summing_to_N_no_functions.py, that defines a function for checking if a string represents an integer or not.
    • Code: summing_to_N_with_functions_2.py A rewrite of summing_to_N_with_functions_1.py summing_to_N_no_functions.py, that uses the check_integer function from number_check.py to check if a string represents an integer or not. At this point, the code here is easy to read and accomplishes what we wanted, namely to print out the sum of integers from 0 to N, and to not crash in any situation.
    • Code: list_to_string.py and list_to_string_main.py. A function concatenating a list of strings into a single string.
    • Code: var1_var2.py. An exercise in separating variables with the same name appearing at different namespaces, and determining which namespace and which variable are visible at each moment.
    • Code: find_substrings.py. An example of a function returning multiple arguments. It takes as inputs two strings, and it returns the number and list of positions of occurrences of the second string in the first string.

• Lecture 11: Thu 7/25 - Program Execution.
  • Book reading: Section 8.1.1.
  • Slides: Program State and Program Execution. PDF, PPT.
    • Code: example1.py. An example of a program where, to understand the result of that program, we need to keep track of separate namespaces.
    • Code: example2.py. An example of definition and usage of a recursive function. Calling that function results in the creation of multiple namespaces that exist at the same time, and that correspond to different calls to the same function.
    • Code: example3.py. A variation of the previous example, that computes the factorial of a number, and does some error checking.
    • Code: example4.py. Another example of a program where, to understand the result of that program, we need to keep track of separate namespaces.
    • Code: example5.py. Yet another example of a program where, to understand the result of that program, we need to keep track of separate namespaces.
    • Code: example6.py. Yet another example of a program where, to understand the result of that program, we need to keep track of separate namespaces. This program involves strings passed as arguments to a function.
    • Code: example7.py. An example of a function creating and returning a list. In particular, function1(num1, num2) returns a list of all even numbers between num1 and num2, as long as num1 and num2 are integers.

• Lecture 12: Mon 7/29 - File input/output.
  • Book reading: Chapter 5.
  • Slides: File input/output. PDF, PPT (last updated: 07/30/2013, 10:00am)
    • Data: to run several of the programs provided below, you should download file1.txt and hello2.txt and place them at the same folder where you place the programs you want to run.
    • Code: print_file.py. An example of a program that reads a file, and prints the contents of the file on the screen.
    • Code: print_file_no_repeats.py. An example of an INCORRECT attempt to print the contents of a file twice.
    • Code: print_file_repeats1.py. An example of a correct attempt to print the contents of a file twice, using the readlines method.
    • Code: print_file_repeats2.py. An example of a correct attempt to print the contents of a file twice, by opening and closing the file twice.
    • Code: file_length.py. A program measuring the size of a file.
    • Code: file_length_function.py. A program measuring the size of a file, using a function.
    • Code: count_words.py. A program counting the number of words in a file.
    • Code: writing_simple.py. A program creating a file and writing some text on that file.
    • Code: writing_copy.py. A program making a copy of a text file.
    • Code: writing_upper.py. A program that reads a text file, converts the text to upper case, and saves the result in another file.
    • Code: phonebook1.py. A first, incomplete version of a program that implements a phonebook application.

• Lecture 13: Tue 7/30 - File input/output (continued), phonebook application.
  • See slides from previous lecture.
    • Data: to run the phonebook program listed below, you should download phonebook.txt and place it at the same folder as the phonebook program.
    • Code: phonebook2.py. A second, still incomplete version of a program that implements a phonebook application.

• Lecture 14: Wed 7/31 - Dictionaries, phonebook application (continued)
  • Book reading: Sections 9.1, 9.2.
  • Slides: Dictionaries. PDF, PPT (last updated: 08/06/2013, 9:10am)
  • Slides: More on dictionaries. PDF, PPT (author: Chris Conly).
    • Data: to run the phonebook program listed below, you should download phonebook.txt and place it at the same folder as the phonebook program.
    • Code: phonebook3.py. A complete version of the phonebook application.
    • Data: to run the word frequency counting programs listed below, you should download file1.txt and place it at the same folder as those programs.
    • Code: word_count_take0.py. An initial version of a program that counts word frequencies in a file.
    • Code: word_count_take1.py. A somewhat improved version of a program that counts word frequencies in a file. Here, the printout looks nicer.
    • Code: word_count_take2.py. More improvements for the program that counts word frequencies in a file. Here, the results are case-insensitive, so that words like "The" and "the" are not treated as separate.
    • Code: word_count_take3.py. More improvements for the program that counts word frequencies in a file. Here, punctuation characters are ignored, so that, for example, the program does not treat "people," as a separate word from "people".
    • Code: word_count_take4.py. The final version of the program that counts word frequencies in a file. Here, the words are printed in descending order of their frequency. To achieve that, we create an inverse dictionary mapping frequencies to words.

• Lecture 15: Thu 08/01 - Practice problems, preparation for second midterm.

• Lecture 16: Mon 08/05 - Second Midterm.

• Lecture 17: Tue 08/06 - Formatted output, Master Mind game, code design.
  • Book reading: Sections 4.4, 4.7, Chapter 10.
  • Slides: Formatted output. PDF, PPT.
    • Code: months_days_no_formatting1.py. Printing the 12 months and the length of each month, without formatting.
    • Code: months_days_no_formatting2.py. A variation of the previous program. Here, format specifiers are used in the print statement, but the output is the same as before, because the format specifiers do not do anything useful.
    • Code: months_days_with_formatting.py. A variation of the previous two programs, that prints the months and days so that the month column is aligned and the day column is aligned.
    • Code: formatted_matrix.py. Code that prints a 3x3 matrix in various ways, both unformatted and formatted.
  • Slides: Master Mind game, code design. PDF, PPT.
    • Code: mastermind_08_07_2012.py. A complete Master Mind implementation. The implementation allows playing both a game where the computer picks a number and the human guesses, and a game where the human picks a number and the computer guesses.

• Lecture 18: Thu 08/08 - Practice problems, preparation for final exam.