Homework Exercises
CSCI 127: Introduction to Computer Science
Hunter College, City University of New York
Spring 2026

All students registered by Friday, January 23, are sent a Gradescope registration invitation to the email on record on their Brightspace account. If you did not receive the email or would like to use a different account, fill in the form on Brightspace. Include that you not receive a Gradescope invitation, your preferred email, and your EmpID. We will manually generate an invitation. As a default, we use your name as it appears in Brightspace/CUNYFirst (to update CUNYFirst, see changing your personal information). If you prefer a different name for Gradescope, include it, and we will update the Gradescope registration.

General Notes

Learning programming is like learning a foreign language: you will learn more (with less work) if you practice every day. Some of the programs below are easy; some will take more time. We suggest you set aside a block of time most days to work on programming and the course.

The programs build on the concepts and code developed during lecture, lab, and through the reading. Mastery of material is assessed via

Autograding of the programs submitted to Gradescope,
The weekly written quizzes with questions about the programs you wrote and concepts from lecture and lab,
The oral code reviews where, each week, you code a program in IDLE, and
The paper final exam which covers all material from the semester.

While you are encouraged to work with others, all work submitted must be your own. As a rule of thumb, you must do your own typing. If it is not from the book or class webpage and you did not type it, it is plagiarism. For the first incident, your grade will be a 0 for the assignment (even for cases where you typed the program but others submitted it as their own). For the second incident of cheating or plagiarism, your grade will be a 0 for the homework component of the grade (20% of your overall grade). For the third incident, you will fail the class. We report all incidents to the Office of Student Affairs.

Autograder Notes

The majority of the programs this semester are written in Python (see Lab 1 for getting started with Python); it is noted below when other formats or languages are used. For Python programs, the autograder expects a .py file, using only the specified libraries, and does not accept iPython/Jupyter notebooks. Since all assignments are designed to be uploaded as a single file, the autograder is set up for direct file upload instead of Github. If submitting directly (drop-and-drag onto the webpage), the file name is flexible but must have the extension .py, unless otherwise noted. Also, to receive full credit, the code should be compatible with Python 3.10 (the default for the Gradescope autograders).

To get full credit for a program, the file must include in the opening comment:

Your name, as it appears in your Gradescope registration.
The email you are using for Gradescope.

For example, for the student, Thomas Hunter, his first program might be:

"""
Name:  Thomas Hunter
Email: thomas.hunter1870@hunter.cuny.edu
Date: September 1, 2025
This program prints: Hello, Thomas Hunter
"""

print("Hello, Thomas Hunter")

For each program, the upper right hand side of the description contains the due date, suggested reading, and, when applicable, the available libraries. When testing your Python programs, the autograder uses Python 3.10 and has available the libraries listed. If the available libraries is none, no additional libraries are used (e.g. no import statement is needed in your program).

You may submit your assignments up to three weeks before the due date and are encouraged to work ahead. To receive credit, assignments must be submitted by the deadline to Gradescope. For more information on using Gradescope, see Lab 1. Since Gradescope gives limited feedback, run your program first locally (on your computer or a lab computer) where the compiler messages will pinpoint errors and help debug your code. For example, if Gradescope gives you a "The autograder failed to execute..." error, it means your program has an error (in this case, it's usually the file contains non-Python commands.). The local Python compiler will give the line of your file with the error, where Gradescope will only say that there's a general problem. For more information on installing Python on your computer, see the installation guides.

Homework Exercises

Due Date: 5pm, Friday, January 30
Reading: Chapter 1 & Lab 1
Available Libraries: none

Hello

Write a program that prints Hello followed by your name to the screen. For example, if your name is Thomas Hunter, when your program is run, it would print:
```
Hello, Thomas Hunter
```
Due Date: 5pm, Monday, February 2
Reading: Chapter 4 & Lab 1
Available Libraries: turtle

Triangle

Write a program that draws a triangle using the turtle library.

Note: Whenever submitting a turtle program, choose a name for your file that is not turtle.py. When executing the import turtle statement, the computer first looks in the folder where the file is saved for the turtle module and then in the libraries (and other places on the path). If you name your file turtle.py, it thinks the module is itself, causing all kinds of errors. To avoid this, name your program something like myTurtle.py or program2.py.

Due Date: 5pm, Wednesday, February 4
Reading: Chapter 4 & Lab 1
Available Libraries: turtle

Turtle Drawing

Write a program to draw your dream home using turtles. The initial part of the code is provided. This must be your own design and, as with all programs, you must be the author of your own code and do your own typing.
You can let your imagination free, the only requirements are:
1. you must use at least 3 different colors
2. your turtle must walk at least 500 steps
```
"""
Your Name
Your Email		
"""
import turtle

t = turtle.Turtle()
t.hideturtle() # Hide the turtle

"""
TODO: finish the rest of the program to draw your dream home
Requirements:  Use at least 3 different colors and walk at least 500 steps
"""
```
Note: For testing purposes we support the following subset of turtle commands
```
backward, color, colormode, forward, goto, hideturtle, home, left, pendown,
penup, pensize, right, shape, showturtle, speed, stamp
```
Please use ONLY these commands in your programs.
Due Date: 5pm, Thursday, February 5
Reading: Chapter 1 & Lab 1
Available Libraries: none

Multiple Greetings

Write a program that will print Welcome! multiple times. The number of times depends on your EmplID number. Take the last 2 digits of your EmplID number and add 10. For example, if your EmplID ends in 13, the number of times you repeat the message is 13+10 = 23.
For example, with an EmplID ending in 02, you would repeat the message 12 times:
```
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
Welcome!
```

Due Date: 5pm, Friday, February 6
Reading: Chapter 4 & Lab 1
Available Libraries: turtle

Flower

Write a program that implements the pseudocode ("informal high-level description of the operating principle of a computer program or other algorithm") below:

"""
Your Name
Your Email		
"""
import turtle

t = turtle.Turtle()
t.speed(0)     # Set the turtle's speed to 0 (fastest)
t.pensize(2)   # Set the turtle's pen size to 2
t.hideturtle() # Hide the turtle

"""
TODO: implement the following pseudocode:
Repeat 36 times: 
  Repeat 3 times: 
    Change the color to pink.
    Walk forward 80 steps.  
    Turn right 60 degrees. 
    Change the color to red.
    Walk forward 80 steps.  
    Turn right 60 degrees.
  Turn right 10 degrees.
"""

Your output should look like this:

Due Date: 5pm, Monday, February 9
Reading: Chapter 2 & Lab 2
Available Libraries: none

Upper & Lower

Using the string commands introduced in Lab 2, write a Python program that prompts the user for a message, and then prints the message, the message in lower case letters, and the message in upper case letters.

A sample run of your program should look like:
```
Enter a message:  Mihi cura futuri
Mihi cura futuri
mihi cura futuri
MIHI CURA FUTURI
```
Another run:
```
Enter a message:  I love Python!
I love Python!
i love python!
I LOVE PYTHON!
```
Hint: Your program should be able to take any phrase the user enters and prints it, prints it in lower case letters, and prints it in upper case letters. To do that, you need to store the phrase in a variable and print variations of the stored variable. See "More Useful String Methods" in Lab 2.
Due Date: 5pm, Wednesday, February 11
Reading: Chapter 2 & Lab 2
Available Libraries: none

Lowercase ASCII

Write a program that prompts the user to enter a phrase, converts the phrase to lowercase, and then prints out each lowercase character and its corresponding ASCII code.

A sample run of your program should look like:
```
Enter a phrase: abc
a 97
b 98
c 99
```
And another sample run:
```
Enter a phrase: ABC
a 97
b 98
c 99
```
Another run, with a longer phrase:
```
Enter a phrase:  I love Python!
i 105
  32
l 108
o 111
v 118
e 101
  32
p 112
y 121
t 116
h 104
o 111
n 110
! 33
```
Hint: The first step is to ask the user for input (see Section 2 of Lab 2). If c is a character, ord(c) returns its ASCII code. For example, if c is 'i', then ord(c) returns 105. See Lab 2 for more on ASCII and characters.

Due Date: 5pm, Friday, February 13
Reading: Chapter 4 & Lab 2
Available Libraries: turtle

Expanding Star-burst

Write a program, using the turtle library, that implements the pseudocode below:
```
Set the speed to 0.
Set the pen size to 3.
Hide the turtle.

For i = 20, 22, ..., 114:
  Change the color to "cyan" 
  Walk forward i steps
  Turn left 60 degrees
  Change the color to "blue" 
  Walk forward i steps
  Turn right 120 degrees
```
Your output should look similar to:

Hint: Use range() with a step parameter to generate every other number. See examples of range(start,stop,step) in Section 4 of Lab 2.
Due Date: 5pm, Wednesday, February 18
Reading: Chapter 2 & Lab 2
Available Libraries: none

Acronyms

Write a program that prompts the user for a phrase and creates an acronym, consisting of the first letters of each word, in uppercase.

To approach a problem, it is useful to break it into steps:
1. Prompt for a phrase & read it into a variable.
2. Make the phrase upper case.
3. Print the phrase.
4. Split up the phrase into words.
5. Take the first letter of each word (keep in mind that split() returns a list of the words ), concatenate and make an acronym of it.
6. Print the acronym.
Now translate the above pseudocode (informal but detailed description of the steps in a program) into python and test that your program works as follows:
```
Enter a phrase:  City University New York
Your phrase in capital letters:  CITY UNIVERSITY NEW YORK
Acronym:  CUNY
```
And another run:
```
Enter a phrase:  Hunter College
Your phrase in capital letters:  HUNTER COLLEGE
Acronym:  HC
```
Hint: See examples of looping through strings in Section 4 of Lab 2.
Due Date: 5pm, Thursday, February 19
Reading: Chapter 4 & Lab 3
Available Libraries: turtle

Shades of Pink

Modify the program from Lab 3 to show the shades of pink.
Hint: think about which combined pair in (red, green, blue) might give you the color pink.

Your output should look similar to:
Due Date: 5pm, Friday, February 20
Reading: Chapter 2 & Lab 2
Available Libraries: none

Word Count

Write a program that asks the user for a phrase, and prints out the number of words in the phrase. Your program should repeat this for 4 more phrases (a total of 5 phrases):

The output of your program should be:
```
Enter phrase: This is my letter to the World
7
Enter phrase: That never wrote to Me-
5
Enter phrase: The simple News that Nature told-
6
Enter phrase: With tender Majesty
3
Enter phrase: Emily Dickinson
2
```
Due Date: 5pm, Monday, February 23
Reading: Chapter 2 & Lab 2
Available Libraries: none

Every 3rd Word Challenge

Write a program that:
- Prompts the user to enter a sentence
- Splits the input into individual words
- Prints every 3rd word from the input, starting with the first word (at index 0)
- Each selected word should be printed on its own line
A sample run of your program should be:
```
Enter a sentence: The crafty clever Python slithers through code hunting for bugs hiding in nested loops
The
Python
code
bugs
nested
```
Hint: Use split() to break the string into a list of words, then use range() with a step parameter to access every 3rd element and len() to get the length of the list as stop parameter. See examples of range(start,stop,step) in Section 4 of Lab 2.
Due Date: 5pm, Wednesday, February 25
Reading: Chapter 2, Chapter 4 & Lab 3
Available Libraries: turtle

Color Stamps

Write a program that asks the user for a color in hexadecimal notation, moves a turtle forward 20 steps, and then stamps out a turtle shape that color. Your program should repeat this for 4 more colors in hexadecimal notation (a total of 5 turtle stamps and moves forward).

For example, if you ran your program and the user entered:
```
Enter color (as hex): #0000FF
Enter color (as hex): #0000B8
Enter color (as hex): #000087
Enter color (as hex): #000043
Enter color (as hex): #000011
```
The output would be:
Due Date: 5pm, Thursday, February 26
Reading: Section 2.8, Chapter 4, Lab 2 & Lab 4
Available Libraries: turtle

Turning Turtle

Write a program that asks the user for 5 whole (integer) numbers. For each number, turn the turtle left the degrees entered and then the turtle should move forward 100.
A sample run of your program should look like:
```
Enter a number: 270
Enter a number: 100
Enter a number: 190
Enter a number: 200
Enter a number: 80
```
and the output should look similar to:

Due Date: 5pm, Friday, February 27
Reading: Lecture 2 & Chapter 2
Available Libraries: none

Caesar Cipher

(The cipher disk above shifts 'A' to 'N', 'B' to 'O', ... 'Z' to 'M', or a shift of 13. From secretcodebreaker.com)

Write a program that prompts the user to enter a word and the amount to shift, and then prints out the word with each letter shifted right by that amount. For example, if the shift was 13 (as in the figure above), then, 'a' becomes 'n', 'b' becomes 'o', ... 'y' becomes 'l', and 'z' becomes 'm'.
Assume that all inputted words are in lower case letters: 'a',...,'z'.
A sample run of your program should look like:
```
Enter an all-small-letter string: zebra
Enter a non-negative int to shift: 13
Encoded string: mroen
```
Here is another sample run of your program.
```
Enter an all-small-letter string: owqfka
Enter a non-negative int to shift: 6
Encoded string: ucwlqg
```
Hint: See the example programs from Lecture 2.

Due Date: 5pm, Monday, March 2
Reading: Lecture 3, Section 9.7 & Lab 2
Available Libraries: none

Slicing Loop

Implement the following piece of pseudocode as a complete program:

1.  Prompt the user to enter a string and call it s.
2.  Let ls be the length of s.
3.  For i in 0, 1, ..., ls-1:
4.     Print s[:i]
5.  For i in 0, 1, ..., ls-1:
6.     Print s[i:]
5.  Print a closing statement

A sample run of your program should look like:

Enter string: a man a plan a canal panama

which would output:

a
a
a m
a ma
a man
a man
a man a
a man a
a man a p
a man a pl
a man a pla
a man a plan
a man a plan
a man a plan a
a man a plan a
a man a plan a c
a man a plan a ca
a man a plan a can
a man a plan a cana
a man a plan a canal
a man a plan a canal
a man a plan a canal p
a man a plan a canal pa
a man a plan a canal pan
a man a plan a canal pana
a man a plan a canal panam
a man a plan a canal panama
man a plan a canal panama
man a plan a canal panama
an a plan a canal panama
n a plan a canal panama
a plan a canal panama
a plan a canal panama
plan a canal panama
plan a canal panama
lan a canal panama
an a canal panama
n a canal panama
a canal panama
a canal panama
canal panama
canal panama
anal panama
nal panama
al panama
l panama
panama
panama
anama
nama
ama
ma
a

Thank you for using my program!

Due Date: 5pm, Tuesday, March 3
Reading: Chapter 2, Chapter 7 & Lab 4
Available Libraries: none

DNA

We can store DNA sequences as strings. These strings are made up of the letters A, C, G, and T. For a given DNA string, the GC-content is the percent of the string that is C or G, written as a decimal.

Write a program that prompts the user for a DNA string, and then prints the length and GC-content of that string.

A sample run of the program:
```
Enter a DNA string:  ACGCCCGGGATG
Length is 12
GC-content is 0.75
```
Hint: See Lab 4. You can use a for-loop to go through each character in the string, and count each time you encounter a 'C' or 'G'. You can use an if-statment to check what kind of character the loop is currently on. Alternatively, you can use the count() method introduced in Lab 2 to get the total occurrences of 'C' and 'G' in the string.
Due Date: 5pm, Wednesday, March 4
Reading: Section 8.11, Lab 4 & Numpy Tutorial
Available Libraries: numpy, matplotlib

Logo

Write a program that creates a 'U' logo for university on a 30x30 grid. Your program should ask the user for the red, green, and blue for the color of their logo, and the file to save the image.

A sample run using Hunter College Purple (Pantone 267):
```
Enter amount of red:  0.373
Enter amount of green:  0.145
Enter amount of blue:  0.624
Enter file name:  hunterPurple_U.png
```
The resulting file is:

The grading script is expecting:
- The grid to be 30 x 30.
- The color of the 'U' is the amount of red, blue, and green specified, as a value between 0 and 1.0.
- The left side of the 'U' should be the left third of the image; the bottom part of the 'U' should be the bottom third of the image; and the right part of the 'U' should be the the right third of the image.
- The remaining pixels in the image should be white (100% red, 100% green, and 100% blue).
Note: before submitting your program for grading, remove the commands that show the image (i.e. the ones that pop up the graphics window with the image). The program is graded on a server on the cloud and does not have a graphics window, so, the plt.show() and plt.imshow() commands will give an error. Instead, the files your program produces are compared pixel-by-pixel to the answer to check for correctness.

Due Date: 5pm, Thursday, March 5
Reading: Section 8.11, Lab 4 & Numpy Tutorial
Available Libraries: matplotlib, numpy

Topographic Map

Modify the map-making program from Lab 4 to make the coastline outline (where elevation is equal to 0) black.

Your resulting map should look like:

and be saved to a file called black_outline_topo.png.
Note: before submitting your program for grading, remove the commands that show the image (i.e. the ones that pop up the graphics window with the image). The program is graded on a server on the cloud and does not have a graphics window, so, the plt.show() and plt.imshow() commands will give an error. Instead, the files your program produces are compared pixel-by-pixel to the answer to check for correctness.

Due Date: 5pm, Friday, March 6
Reading: Section 10.23, Chapter 4 & Lab 4
Available Libraries: none

Two-Part Numbers

Write a program that identifies all two-part numbers from a string and returns a list of those numbers. In the input string, each number is separated by a comma followed by a space: ', ', and two-part numbers contain a '-'.

For example, if you ran your program and the user entered:
```
Enter numbers, separated by commas: twenty, four, thirty-one, sixty-six, eight
A list of the two-part numbers:  ["thirty-one", "sixty-six"]
```
Hint: See Section 4 in Lab 4.

Due Date: 5pm, Monday, March 9
Reading: Lab 4 & Numpy Tutorial
Available Libraries: matplotlib, numpy

Grayscale Image

Write a program that asks the user for a name of an image .png file and the name of an output file. The program then converts the image to grayscale and saves the grayscale image to the specified output file.

There are many ways to convert color images to grayscale (see Grayscale Algorithms for a nice overview).
For this program, we are setting each channel of a pixel to its green value. That is, your program should then set the red channel values to the green channel values, as well as the blue channel values to the green channel values. For example, a single pixel at (i,j) of the image img would be changed to:
```
img[i,j,0] = img[i,j,1]  #change value of red channel to value of green channel
img[i,j,2] = img[i,j,1]  #change value of blue channel to value of green channel
```
A sample run of your program should look like:
```
Enter name of the input file:  csBridge.png
Enter name of the output file:  gray_bridge.png
```
The sample input file and the resulting grayscale image:

Note: before submitting your program for grading, remove the commands that show the image (i.e. the ones that pop up the graphics window with the image). The program is graded on a server on the cloud and does not have a graphics window, so, the plt.show() and plt.imshow() commands will give an error. Instead, the files your program produces are compared pixel-by-pixel to the answer to check for correctness.
Hint: See Lab 3. Think about how you can uses numpy slices to change every pixel.

Due Date: 5pm, Tuesday, March 10
Reading: Burch's Logic & Circuits & Lab 5
Available Libraries: N/A

NOR Circuit

Build a circuit that has the same behavior as a nor gate (i.e. true only when all inputs are false) using only and, or, and not gates.

Save your expression to a text file. See Lab 5 for the format for submitting logical expressions to Gradescope.
Due Date: 5pm, Wednesday, March 11
Reading: Burch's Logic & Circuits & Lab 5
Available Libraries: N/A

Majority Circuit

Write a logical expression that is equivalent to the circuit that computes the majority of 3 inputs, called in1, in2, in3:
- If two or more of the inputs are True, then your expression should evaluate to True.
- Otherwise (two or more of the inputs are False), then your expression should evaluate to False.
Save your expression to a text file. See Lab 5 for the format for submitting logical expressions to Gradescope.

Hint: See Lab 5.
Due Date: 5pm, Thursday, March 12
Reading: Chapter 7 & Lab 4
Available Libraries: turtle

Turtle String

The program turtleString.py takes a string as input and uses that string to control what the turtle draws on the screen (inspired by code.org's graph paper programming). Currently, the program processes the following commands:

'F': moves the turtle forward 50 steps
'L': turns the turtle 90 degrees to the left
'R': turns the turtle 90 degrees to the right
'^': lifts the pen
'v': lowers the pen

FLFLFLFL^FFFvFLFLFLFL

Modify this program to allow the user to also specify with the following symbols:

'T': change the shape to triangle
'C': change the shape to circle
'c': change the pen color to cyan
'o': change the pen color to orange
'B': change the pen size to 5 (Big pen)
's': change the pen size to 2 (small pen)
'S': makes the turtle stamp

An example with the new symbols and string CcSLBTFSRsoFCSLFBcSTLFoS would create the image:

Due Date: 5pm, Friday, March 13
Reading: Burch's Logic & Circuits & Lab 5
Available Libraries: N/A

Binary Number Incrementer

Logical gates can be used to do arithmetic on binary numbers. For example, we can write a logical circuit whose output is one more than the inputted number. Our inputs are in1 and in2 and the outputs are stored in out1, out2, and out3.

Here is a table of the inputs and outputs:

Inputs Outputs

Decimal
Number in1 in2 Decimal
Number out1 out2 out3

0 0 0 1 0 0 1

1 0 1 2 0 1 0

2 1 0 3 0 1 1

3 1 1 4 1 0 0

Submit a text file with each of the outputs on a separate line:
```
"""
Name:  YourNameHere
Date:  March 2025
Logical expressions for a 4-bit incrementer
"""

out1 = ...
out2 = ...
out3 = ...
		
```
Where "..." is replaced by your logical expression (see Lab 5 for hints and formatting help).
Note: here's a quick review of binary numbers.

Due Date: 5pm, Monday, March 16
Reading: Lecture 4, Lab 4
Available Libraries: none

Air Quality Index Alert

Write a program that asks for the Air Quality Index (AQI) value and prints out:
- "Good Air Quality" if the AQI is between 0 and 50 (inclusive),
- "Moderate Air Quality" if the AQI is between 51 and 100 (inclusive),
- "Unhealthy for Sensitive Groups" if the AQI is between 101 and 150 (inclusive),
- "Unhealthy Air Quality" if the AQI is between 151 and 200 (inclusive) and
- "Very Unhealthy Air Quality" if the AQI is above 200.
A sample run:
```
Enter AQI value: 125
Unhealthy for Sensitive Groups
```
Note: "inclusive" for a range of numbers means that it includes the endpoints. For example, "between 4 and 8, inclusive" means all values that are greater than or equal to 4 and are also less than or equal to 8.

Due Date: 5pm, Tuesday, March 17
Reading: 10-mins to Pandas, DC Pandas, Lab 6
Available Libraries: pandas

Minimal Temperatures

In Lab 6, we wrote a program that computed the average rainfall from Australian weather data. Modify the program to ask the user for the name of a CSV file and then to print out, using the data from the CSV file:
- The lowest temperature recorded across all locations and dates.
- The lowest temperature for each location across all dates.
For example, running the program on rain_A.csv (a smaller version of the CSV file from the lab that's contains only the cities that start with 'A'):
```
Enter CSV file name: rain_A.csv
Overall min temp: -5.2

Minimum temperature by location:
Location
Adelaide        0.7
Albany          1.8
Albury         -2.8
AliceSprings   -5.2		
```

Inputs	Outputs
Decimal Number	in1	in2	Decimal Number	out1	out2	out3
0	0	0	1	0	0	1
1	0	1	2	0	1	0
2	1	0	3	0	1	1
3	1	1	4	1	0	0

Due Date: 5pm, Wednesday, March 18
Reading: 10-mins to Pandas, DC Pandas, Lab 6
Available Libraries: pandas

Store Inventory

Using pandas, write a program that asks the user for a store inventory file, in comma separated value (CSV) format, reads in the corresponding CSV file, calculates a 20% discount on all prices, and prints out the inventory with a new column named Discounted-Price showing the discounted prices. Assume that the CSV files have the columns: "Item", "Price", and "Quantity".

For example if the CSV file, inventory.csv, contained:

Item Price Quantity

Laptop 1000.00 5

Mouse 25.00 20

Keyboard 75.00 15

Monitor5 300.00 8

A sample run of your program would be:
Enter inventory file name: inventory.csv Discounted inventory: Item Price Quantity Discounted_Price 0 Laptop 1000.0 5 800.0 1 Mouse 25.0 20 20.0 2 Keyboard 75.0 15 60.0 3 Monitor 300.0 8 240.0

Due Date: 5pm, Thursday, March 19
Reading: GitHub Guide, Lab 6
Available Libraries: N/A

GitHub

In Lab 6, you created a GitHub account. Submit a text file with the name of your account. The grading script is expecting a file with the format:
""" Name: Your_name Email: Your_eamil Account name for my GitHub account """" AccountNameGoesHere

Note: it takes a few minutes for a newly created GitHub account to be visible. If you submit to Gradescope and get a message that the account doesn't exist, wait a few minutes and try again.

Due Date: 5pm, Monday, March 23
Reading: Lab 6, Ubuntu Terminal
Available Libraries: N/A

Hello (Shell Script)

Write a shell script that prints Hello, Shell to the screen.

Submit a single text file containing your Unix shell commands. See Lab 6 for details.

Note: for comments, shell scripts use # in front of lines (instead of the block comments surrounded by """ """) and the first line is the "shebang" line. For a proper shell script, your file should start:

#!/bin/bash #Name: YourNameHere #Email: YourEmailHere

Due Date: 5pm, Tuesday, March 24
Reading: Lab 7 & Section 6.8
Available Libraries: none

Hello Two Ways

Write a Python program that contains a function called, main(). Your function should print out a greeting to you by name. For example, if your name is Thomas Hunter, invoking main() would print:

Hello, Thomas Hunter

You should use conditional execution, so your file can be run as a standalone program or imported so the function can be used elsewhere.

To test your program, we will run it two ways:

We will run it as a stand-alone program and see that it outputs the greeting. If your program is called, student.py, then we would run it, python3 student.py, to see that it prints the greeting.

We will import your file and directly call the function. If your program is called, student.py, we would import it into a Python program, import student, and in that program, call your function, student.main(), to see that it prints the greeting.

Hint: See Section 4 of Lab 7 for details on conditional execution.

Due Date: 5pm, Wednesday, March 25
Reading: Think CS Chapter 6, Chapter 7, Lab 5 & Numpy Tutorial
Available Libraries: matplotlib, numpy

Counting Red Pixels

Write a function count_red_pixels() that takes the filename of an image and returns the number of pixels where the red channel is the dominant color. A pixel is considered "red-dominant" if its red value is greater than both its green value AND greater than its blue value.
For example, a pixel with RGB values (200, 150, 100) would be counted as red-dominant because 200 > 150 and 200 > 100. However, a pixel with RGB values (200, 250, 100) would not be counted because the green value (250) is greater than the red value (200).

An example, using the file red_forest.png as the input file

the following code, using your function:
red_count = count_red_pixels('red_forest.png') print(red_count)

will output
207278

In another example, using the file green_forest.png as the input file

the following code, using your function:
red_count = count_red_pixels('green_forest.png') print(red_count)

will output
106

Note: The grading script does not run the whole program, but instead tests your function separately ('unit tests') to determine correctness. As such, the function name must match exactly (else, the scripts cannot find it). Before submitting your program for grading, remove any commands that are outside a function definition. To test the function you wrote, we import your file and then call the function directly. Code outside of function definitions will give compilation errors and prevents the tests from completing (giving a grade of 0). If you have extra code for testing and such, either comment it out before submitting, or use conditional execution (see Lab 7).

Hint: See Section 2 of Lab 5, Snow Pack in California, for an example of counting pixels.

Due Date: 5pm, Monday, March 26
Reading: 10-mins to Pandas, DC Pandas, Lab 7
Available Libraries: pandas

Library Checkout Analysis

The Seattle Public Library provides data on item checkouts. Each row in the dataset represents checkout activity for a specific title during a given month. The dataset includes information about what was checked out (books, movies, music, etc.), how it was checked out (physical vs. digital), who published it, and when.

Adapt the parking ticket program from Lab 7 to analyze library checkout data. Your program should:

Ask the user for the name of the input CSV file.

Ask the user for the attribute (column name) to analyze.

Display the top 5 values for that attribute.

Valid attributes the user may enter:

usageclass - Whether item is Physical or Digital

checkouttype - The system/vendor used for checkout

materialtype - Type of item (book, song, movie, etc.)

publisher - Publisher of the item

checkoutyear - Year of checkout

Use this sample dataset for testing: seattle_library.csv

A sample run:

Enter CSV file name: seattle_library.csv Enter attribute: materialtype The top 5 values for materialtype are: materialtype BOOK 427 EBOOK 200 SOUNDDISC 99 VIDEODISC 88 SONG 79 Name: count, dtype: int64

And another run:

Enter CSV file name: seattle_library.csv Enter attribute: usageclass The top 5 values for usageclass are: usageclass Physical 621 Digital 379 Name: count, dtype: int64

And one more run:

Enter CSV file name: seattle_library.csv TEnter attribute: checkoutyear The top 5 values for checkoutyear are: checkoutyear 2016 989 2024 10 2025 1 Name: count, dtype: int64

Due Date: 5pm, Friday, March 27
Reading: Section 6.8 & Lab 7
Available Libraries: turtle

Rainbow Star

Write a program, using function main() that implements the following pseudocode.
Note: the pseudocode refers to the body of the function and does not illustrate the function definition.
""" TODO: implement the following pseudocode inside a main() function: Create a turtle Set the turtle's speed to 0 Set the turtle's pen size to 2 Hide the turtle Create a list with ["red", "cyan", "blue", "orange"] repeated 12 times Create a list with the numbers 20, 22, 24, ..., 114 Zip the two lists For each color and distance in the zipped lists: Set the turtle's color to the current color Move forward by the current distance Turn left 120 degrees Move forward by the current distance again Turn right 65 degrees """

Hint: You can repeat a list using *
Example: [1, 2] * 3 creates [1, 2, 1, 2, 1, 2]
Hint: Use list(range(start, stop, step)) to create a list of numbers
Example: list(range(10, 30, 5)) creates [10, 15, 20, 25]
Hint: Use zip() to pair elements from two lists together. See Lab 7 Section 2
Your output should look like this:

Due Date: 5pm, Thursday, March 30
Reading: Section 7.4, Lab 4, Lab 7 and Lab 8
Available Libraries: none

Letter to GPA

Write the function letter_to_gpa() which takes a string representing a letter grade and returns the corresponding GPA value as a float.

If the user provides a string that does not correspond to a valid letter grade, your function should return: -1.0

Valid letter grades are: A, A-, B+, B, B-, C+, C, C-, D+, D, F (case-insensitive).

Use the following GPA scale:
A: 4.0 A-: 3.7 B+: 3.3 B: 3.0 B-: 2.7 C+: 2.3 C: 2.0 D: 1.0 F: 0.0

A sample call of the function:
print("Converting A- to", letter_to_gpa("A-"))

would print:

Converting A- to 3.7

And another example call of the function:
grade = "B+" print("Converting", grade, "to", letter_to_gpa(grade))

would print:

Converting B+ to 3.3

Note: The grading script does not run the whole program, but instead tests your function separately ('unit tests') to determine correctness. As such, the function name must match exactly (else, the scripts cannot find it). Before submitting your program for grading, remove any commands that are outside a function definition. To test the function you wrote, we import your file and then call the function directly. Code outside of function definitions will give compilation errors and prevents the tests from completing (giving a grade of 0). If you have extra code for testing and such, either comment it out before submitting, or use conditional execution (see Lab 7).

Hint: See Lecture 8 for related programs.

Due Date: 5pm, Friday, April 10
Reading: Think CS Chapter 6, Lab 4, Lab 8, & Numpy Tutorial
Available Libraries: matplotlib, numpy

Averaging Images

Fill in the missing functions:

average(region): Takes a region of an image and returns the average red, green, and blue values across the region.
setRegion(region,r,g,b): Takes a region of an image and red, green, and blue values, r, g, b. Sets the region so that all points have red values of r, green values of g, and blue values of b.

The functions are part of a program that averages smaller and smaller regions of an image until the underlying scene is visible (inspired by the elegant koalas to the max).
For example, if you inputted our favorite image, you would see (left to right):

and finally:

A template program, averageImage.py, is available here. You should use this file to get started with your program.

The grading script does not run the whole program, but instead runs each of your functions separately ('unit tests') to determine correctness. As such, the names of the functions must match exactly the ones listed above (else, the scripts cannot find them).

Due Date: 5pm, Monday, April 13
Reading: 10-mins to Pandas, DC Pandas, Lab 6, Lab 7
Available Libraries: pandas, matplotlib

Wondrous Stars

Write a program that, given the 'Stars' dataset will do the following:

Ask the user for the name of the input file.
Ask the user for the name of the column they wish to average (one of Temperature, Luminosity, Radius or Absolute Magnitude)
Print the average of that column for each star type.

Note: To put the data in perspective, keep in mind that these measures are given as multiples of those of the Sun! (image credits: space.com)

A sample run:
Enter file name: stars.csv Enter the name of the column (Temperature, Luminosity, Radius or Absolute Magnitude) you would like to average: Luminosity The average Luminosity for each Star type is: Star type Brown Dwarf 0.000693 Hypergiant 309246.525000 Main Sequence 32067.386275 Red Dwarf 0.005406 Supergiant 301816.250000 White Dwarf 0.002434 Name: Luminosity, dtype: float64

Another sample run:
Enter file name: stars.csv Enter the name of the column (Temperature, Luminosity, Radius or Absolute Magnitude) you would like to average: Temperature The average Temperature for each Star type is: Star type Brown Dwarf 2997.950 Hypergiant 11405.700 Main Sequence 16018.000 Red Dwarf 3283.825 Supergiant 15347.850 White Dwarf 13931.450 Name: Temperature, dtype: float64

Note: You may assume that input is correct (e.g. only expected columns are entered as input)
Hint: You should use groupby() as described in Lab 6.

Due Date: 5pm, Tuesday, April 14
Reading: Think CS Chapter 6 & Lab 8
Available Libraries: turtle

Polygons

Write function polygon, which takes four parameters: a turtle, number of edges, edge length, and color as a string. The functionality of polygon uses turtle object to draw a polygon with number of edges, each edge has edge length, the polygon is in color, where color can be specified in name like "red" or using a hexadecimal representation such as "#00ffff" (green + blue = cyan).
The code of function main to test polygon is as follows:
def main(): tess = turtle.Turtle() polygon(tess, 5, 100, "green") polygon(tess, 6, 60, "#ff00ff") polygon(tess, 7, 70, "#ff0000") turtle.done() if __name__ == '__main__': main()
The above main function produces the following figure.

Note: The grading script does not run the whole program, but instead tests your function separately ('unit tests') to determine correctness. As such, the function name must match exactly (else, the scripts cannot find it). Before submitting your program for grading, remove any commands that are outside a function definition. To test the function you wrote, we import your file and then call the function directly. Code outside of function definitions will give compilation errors and prevents the tests from completing (giving a grade of 0). If you have extra code for testing and such, either comment it out before submitting, or use conditional execution (see Lab 7).

Hint: See Lecture 1 for the general recipe for drawing polygons.

Due Date: 5pm, Wednesday , April 15
Reading: Chapter 12 & Lab 8
Available Libraries: none

Unique Entries

When students visit the lab, their EmpID is stored as an 8-digit string. Many students visit multiple times, but we are interested in the total number of unique visitors to the lab. Write a function unique_visitors() that takes a list of 8-digit strings and returns the number of unique strings that occur.

For example:

ids = ['12345678','11223344','12312323','12345678'] print("The number of unique visitors is ", unique_visitors(ids))
would print:
The number of unique visitors is 3
since there are 4 entries but the first and fourth entries are duplicates of each other.
Note: The grading script does not run the whole program, but instead tests your function separately ('unit tests') to determine correctness. As such, the function name must match exactly (else, the scripts cannot find it). Before submitting your program for grading, remove any commands that are outside a function definition. To test the function you wrote, we import your file and then call the function directly. Code outside of function definitions will give compilation errors and prevents the tests from completing (giving a grade of 0). If you have extra code for testing and such, either comment it out before submitting, or use conditional execution (see Lab 7).

Hint: Use a dictionary to store the IDs and return the length of the dictionary.

Due Date: 5pm, Thursday , April 16
Reading: Chapter 12 & Lab 8
Available Libraries: none

Most Common Word

Write a function most_common() that takes a string and returns the word that occurs most often. You may assume that:

There is exactly one word that occurs most often.

All punctuation has been removed and words are separated by spaces (' ') and all letters are lower-case.

For example:

phrase = "MORE: The more that you read, the more things you will know. The more that you learn, the more places you'll go. --Dr. Seuss" phrase = phrase.lower() punctuation_list = ['.',',','!','?',':',';','\n','\t','-',' '] for pun in punctuation_list: phrase = phrase.replace(pun,' ') print('Phrase unpunctuated:', phrase) print('Most common word:', most_common(phrase))
would print:
Phrase unpunctuated: more the more that you read the more things you will know the more that you learn the more places you'll go dr seuss Most common word: more

since 'more' occurs five times in the phrase, more than any other.
Note: The grading script does not run the whole program, but instead tests your function separately ('unit tests') to determine correctness. As such, the function name must match exactly (else, the scripts cannot find it). Before submitting your program for grading, remove any commands that are outside a function definition. To test the function you wrote, we import your file and then call the function directly. Code outside of function definitions will give compilation errors and prevents the tests from completing (giving a grade of 0). If you have extra code for testing and such, either comment it out before submitting, or use conditional execution (see Lab 7).

Hint: Use a dictionary to count how many times you see each name. When you add a name to the dictionary a second time, also append the name to a list of duplicated names.

More coming soon...

Homework Exercises CSCI 127: Introduction to Computer Science Hunter College, City University of New York Spring 2026

General Notes

Autograder Notes

Homework Exercises

Homework Exercises
CSCI 127: Introduction to Computer Science
Hunter College, City University of New York
Spring 2026