EX02 - One Shot Battleship - COMP110

Overview

Please complete all lessons before attempting to begin this exercise.

The next step in our journey to implementing Battleship is to produce a program that gives the player one shot at guessing your program’s secret boat location. (Of couse, they can play the game multiple times in order to have multiple chances.)

In this exercise, you will print out a grid of boxes instead of just one line, and prompt the user for a row and column for their guess. Level up!

You should follow the steps below for implementing the program one step at a time. To get a sense of where you are going, here is an example of the final game:


    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 2
    Guess a column: 4
    🟦🟦🟦🟦
    🟦🟦🟦⬜
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    Miss!

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 1
    Guess a column: 2
    🟦⬜🟦🟦
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    Close! Correct column, wrong row.

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 3
    Guess a column: 3
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦⬜🟦
    🟦🟦🟦🟦
    Close! Correct row, wrong column.
    
    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 5
    The grid is only 4 by 4. Try again: 3
    Guess a column: 6
    The grid is only 4 by 4. Try again: 2
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟥🟦🟦
    🟦🟦🟦🟦
    Hit!

Permitted Constructs

We expect you to implement this exercise using only the concepts covered in COMP110. If you have prior programming experience, restrict your implementation to only the concepts covered. While there are many ways to implement this program with additional concepts beyond those we have covered, you should not attempt to do so until after submitting this exercise for full credit once the autograder is posted. Gaining additional practice with the fundamentals may feel clunky, but will help ensure you have full command over the concepts we expect you to know. Additionally, it is good practice for working in other programming environments which are more constrained and require creativity to overcome restrictions. For this exercise, you will be penalized for using any kind of loop construct other than a while loop.

Background Lesson: Formatted Strings (f-Strings)

In this exercise, you will need to make use of another advanced string concept: formatted Strings (f-Strings)

Before beginning work on this exercise, you might want to reread the following lesson: LS11 - Unicode, Emoji, Escape Sequences, and f-Strings

Part 0. Setting up the Python Program

In Visual Studio Code, be sure your workspace is open. (Reminder: File > Open Recent > comp110-YYS-workspace is a quick way to reopen it! Where YY is the current year and S is the semeseter: S for Spring, F for Fall.)

Open the Explorer pane (click the icon with two sheets of paper or to to View > Explorer) and expand the Workspace directory.

Right click on the exercises directory and select “New File”. Enter the following filename, being careful to match capitalization and punctuation:

ex02_one_shot_battleship.py

Before beginning work on the program, you should add a docstring to the top of your Python module just as you did in EX00 and EX01. Then, you should add a line with the special variable named __author__ assigned to be a string with your 9-digit student PID. Fill in your 9-digit UNC PID number, without any spaces or dashes, in the __author__ string.

Part 1. Establishing a Secret and Prompting for a Guess – 30 Points

First, you’ll need to establish a few variables: an int for the size of your grid, an int for a secret row, and an int for a secret column. For the purposes of the autograder, hard code your grid size, secret row, and secret column to 4, 3, and 2 respectively.

Go ahead and prompt the user to guess a row and column as shown below. Compare the guesses to the secret variables, to output “Hit!” or “Miss!”.

Additionally, in simple battleship, you would exit if the user gave an invalid input. This time around, we will add the ability to re-input a guess if given an invalid input. With the help of while loops, see if you can continue to prompt the player until they provide a guess that is within the bounds of the size of the grid. Here’s how your program should perform after this step:


    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 3
    Guess a column: 2
    Hit!

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 5
    The grid is only 4 by 4. Try again: 1
    Guess a column: 6
    The grid is only 4 by 4. Try again: 2
    Miss!

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 5
    The grid is only 4 by 4. Try again: 12390
    The grid is only 4 by 4. Try again: 3
    Guess a column: 123589
    The grid is only 4 by 4. Try again: 2
    Hit!

Before you continue on, does this step work correctly if you change the value for the size of your grid? If you set grid size to 5, does the re-input statement say, “The grid is only 5 by 5. Try again:”? Make sure you are using the grid size variable to enforce the bounds of a valid input, and not hard coding a certain number!

Additionally, be sure you are using f-String templates rather than conatenation for text output in this section as introduced in the background lesson.

WARNING: Autograding will very specifically be looking for exactly the format of lines output shown above. You will not see the $ at your command-line prompt in VSCode, you can ignore that part. Otherwise, when you run the program on your machine with the same inputs as above on the first two lines, your printed results should look exactly like it.

Part 2. Print a Grid – 30 Points

In battleship, you normally have a grid of blue boxes instead of just one row of ocean as seen in EX01. Using the concept of while loops, you’ll be able to print out any grid at the size of your choice! Remember, the location of your guess within the grid will contain a red box if you guessed both column and row correctly and a white box if not. If you haven’t already, paste in the following constants:

    BLUE_BOX: str = "\U0001F7E6"
    RED_BOX: str = "\U0001F7E5"
    WHITE_BOX: str = "\U00002B1C"

Since loops are new to your repertoire, we will give you a general strategy for accomplishing this task. Your job will be to translate this plan in English into working Python code.

First, come up with a result box str similar to how you did in EX01, which will either be a red or white box depending on the correctness of the user’s guess.
Then, establish an int counter variable to keep track of which row you are printing starting with 1.
While the row counter variable is less than or equal to the size of the grid, do as follows:
1. Create a str to store your emoji string for a singular row.
2. Create a column counter variable to keep track of how many times you have concatenated an emoji box to the row string, also starting at 1.
3. Test to see if the user’s row guess is equal to the row counter.
  1. If so, while your column counter variable is less than or equal to the size of the grid, do as follows: 1. If the user guess for column is equal to the counter, concatenate the result box (red or white) to the row string. 2. Else, concatenate a blue box to the row string. 3. After the conditional, increase your column counter variable by one so that you do not have an infinite loop.
4. Otherwise:
  1. While the column counter variable is less than or equal to the size of the grid, do the following:
    1. Concatenate a blue box.
    2. Increment your column counter variable by one to avoid an infinite loop.
5. After the if-else blocks, print the emoji string (one row is outputted).
6. Increment your first row counter variable by one to avoid an infinite loop.

Once you have completed this part of the program, your output should look as follows (should the secret row be 3 and secret column be 2.)


    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 2
    Guess a column: 4
    🟦🟦🟦🟦
    🟦🟦🟦⬜
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    Miss!

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 3
    Guess a column: 3
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦⬜🟦
    🟦🟦🟦🟦
    Miss!
    
    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 3
    Guess a column: 2
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟥🟦🟦
    🟦🟦🟦🟦
    Hit!

Part 3. Giving A Hint to Your User – 10 Points

What if your user was very close? Right row, but wrong column? Right column, but wrong row?

Add a couple elif statements to your user feedback (“Hit!” and “Miss” logic). Your program should perform like this after this step (if the secret row is 3 and column is 2):


    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 2
    Guess a column: 4
    🟦🟦🟦🟦
    🟦🟦🟦⬜
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    Miss!

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 1
    Guess a column: 2
    🟦⬜🟦🟦
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    Close! Correct column, wrong row.

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 3
    Guess a column: 4
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦🟦⬜
    🟦🟦🟦🟦
    Close! Correct row, wrong column.

    $ python -m exercises.ex02_one_shot_battleship
    Guess a row: 5
    The grid is only 4 by 4. Try again: 3
    Guess a column: 3
    🟦🟦🟦🟦
    🟦🟦🟦🟦
    🟦🟦⬜🟦
    🟦🟦🟦🟦
    Close! Correct row, wrong column.

And there you have your one-shot battleship! See what happens when you change the secret row and column or the grid size. Just make sure to set them to the specified values before you submit to Gradescope.

Part 4. Style and Documentation Requirements – 20 Points (Manually Graded)

We will manually grade your code and are looking for good choices of meaningful variable names. Your variable names should be descriptive of their purposes. (Loop indexing variables can be short, such as i, or idx.) You should also use the Python snake_case convention where variable names are all lowercase and new words are separated by underscores.

You should add code comments in your own English words to describe what is happening at important stages of your program.

Again, your program should work regardless of the grid’s size. Thus, you should not have any hard-coded numbers (such as 4 for the grid size). All numbers that appear in output and the boundaries of loops should be based on the grid size variable.

Part 5. Type Safety and Linting - 9 Points

The autograder uses industry standard tools for checking the type safety of your programs (e.g. being sure you’re using variables of the correct data types in valid ways) and linting style rules. If you have point deductions on Type Safety or Linting, read through the feedback the autograder gives and it should direct you to the line number in your program with the issue.

Make a Backup Checkpoint “Commit”

As you make progress on this exercise, making backups is encouraged.

Open the Source Control panel (Command Palette: “Show SCM” or click the icon with three circles and lines on the activity panel).
Notice the files listed under Changes. These are files you’ve made modifications to since your last backup.
Move your mouse’s cursor over the word Changes and notice the + symbol that appears. Click that plus symbol to add all changes to the next backup. You will now see the files listed under “Staged Changes”.
- If you do not want to backup all changed files, you can select them individually. For this course you’re encouraged to back everything up.
In the Message box, give a brief description of what you’ve changed and are backing up. This will help you find a specific backup (called a “commit”) if needed. In this case a message such as, “Progress on Exercise 1” will suffice.
Press the Check icon to make a Commit (a version) of your work.
Finally, press the Ellipses icon (…), look for “Pull/Push” submenu, and select “Push to…”, and in the dropdown select your backup repository.

Submit to Gradescope for Grading

All that’s left now is to hand-in your work on Gradescope for grading!

Login to Gradescope and select the assignment named “EX02 - One-shot Battleship”. You’ll see an area to upload a zip file. To produce a zip file for autograding, return back to Visual Studio Code.

If you do not see a Terminal at the bottom of your screen, open the Command Palette and search for “View: Toggle Integrated Terminal”.

Type the following command (all on a single line):

python -m tools.submission exercises/ex02_one_shot_battleship.py

In the file explorer pane, look to find the zip file named “yy.mm.dd-hh.mm-exercises-ex02_one_shot_battleship.py.zip”. The “yy”, “mm”, “dd”, and so on, are timestamps with the current year, month, day, hour, minute. If you right click on this file and select “Reveal in File Explorer” on Windows or “Reveal in Finder” on Mac, the zip file’s location on your computer will open. Upload this file to Gradescope to submit your work for this exercise.

Autograding will take a few moments to complete. If for any reason you aren’t receiving full credit and aren’t sure what to try next, come give us a visit in office hours! –>