Number Comparison¶

Project Goals¶

This programming project invites you to combine what you learned about the basics of Python programming to implement a useful program that compares three numbers that are provided as input to a program. Specifically, the program should return the largest odd number among the provided inputs, provided that at least one of the number is odd. When none of the input values are odd, the program should return the smallest of the three provided values. Along with adding documentation to the provided source code, you will create your own Python functions that use both iteration constructs and conditional logic to implement a correct program that passes the test suite and all checks. As you enhance your technical skills, you will program with tools such as VS Code and a terminal window and the Python programming language and the Poetry package manager.

Project Access¶

If you are a student enrolled in a Computer Science class at Allegheny College, you can access this assignment by clicking the link provided to you in Discord. Once you click this link it will create a GitHub repository that you can clone to your computer by following the general-purpose instructions in the description of the technical skills. Specifically, you will need to use the git clone command to download the project from GitHub to your computer. Now you are ready to add source code and documentation to the project!

Expected Output¶

This project invites you to implement a number comparison program called compare. The program accepts through its command-line three integer values. If you run the program correctly, it will accept as input the three numbers and return the largest odd number as long as at least one of the numbers is odd. In the situation in which none of the numbers are odd, it will return the smallest number. If you run the program with the command poetry run compare --first 4 --second 10 --third 21 it produces this output:

✨ Comparing the numbers 4, 10, and 21!

Looking for the largest odd number ...
... but if there is no odd number, then ...
... looking for the smallest of the three!

Okay, I found the number 21!

😂 It was nice to find an odd number!

Alternatively, if you run the program with the command poetry run compare --first 4 --second 10 --third 20 then it produces output like:

✨ Comparing the numbers 4, 10, and 20!

Looking for the largest odd number ...
... but if there is no odd number, then ...
... looking for the smallest of the three!

Okay, I found the number 4!

🤷 Oh well, there were no odd numbers this time!

If you run the program without specifying one of the required input numbers by using, for instance, the command poetry run compare --first 4 --second 10 then it will not perform number comparison and instead produce an error message like the following:

Usage: compare [OPTIONS]
Try 'compare --help' for help.

Error: Missing option '--third'.

To learn more about how to run this program, you can type the command poetry run compare --help to see the following output showing how to use compare:

Usage: compare [OPTIONS]

  Perform number comparison to find the largest odd number.

Options:
  --first INTEGER       [required]
  --second INTEGER      [required]
  --third INTEGER       [required]
  --install-completion  Install completion for the current shell.
  --show-completion     Show completion for the current shell, to copy it
                        or customize the installation.

  --help                Show this message and exit.

Please note that the provided source code does not contain all of the functionality to produce this output. As explained in the next section, you are invited to add all of the missing features and ensure that compare produces the expected output. Once the program is working correctly, it should produce all of the expected output described in this section.

Adding Functionality¶

If you study the file compare/compare/main.py you will see that it has many TODO markers that designate the parts of the program that you need to implement before compare will produce correct output. If you run the provided test suite with the command poetry run task test you will see that it produces output like the following:

    def test_find_minimum():
        """Confirm that the function can find the minimum of three values."""
        minimum = main.get_minimum(3, 4, 5)
>       assert minimum == 3
E       assert None == 3

tests/test_compare.py:16: AssertionError

Alternatively, running the program with a command like poetry run compare --first 4 --second 10 --third 21 will not produce any output because compare is missing this functionality! As you complete the tasks near each of the TODO markers, all while following the relevant instructions in the description of the technical skills, you should have a version of compare that produces all of the expected output.

The compare program uses the get_minimum function to identify the minimum of three int values. You can read a test case in the test_compare.py test suite to learn more about how compare's get_minimum function should work. For instance, the following test case confirms that when get_minimum receives the inputs 3, 4, and 5 then it should return the value of 3, regardless of the order in which the values are input to the function. Studying the source code of test_find_minimum shows that lines 3, 5, and 7 call the get_minimum function with different orders of the same input values and lines 4, 6, and 8 all confirm that the returned value of minimum is 3.

1
2
3
4
5
6
7
8

def test_find_minimum():
    """Confirm that the function can find the minimum of three values."""
    minimum = main.get_minimum(3, 4, 5)
    assert minimum == 3
    minimum = main.get_minimum(5, 4, 3)
    assert minimum == 3
    minimum = main.get_minimum(4, 3, 5)
    assert minimum == 3

If the get_minimum function works correctly, then you can start to implement and test the get_largest_odd function in the compare program! You can read some test cases in test_compare.py test suite to learn more about how get_largest_odd should work. For example, the following test case confirms that when get_largest_odd receives the values 21, 4, and 17 it will return 21. In contrast, if it receives the inputs 21, 4, and 117 it will return the value of 117 because that number is also odd and larger than 21!

1
2
3
4
5
6
7
8

def test_largest_odd_can_find_one():
    """Confirm that it is possible to find the largest odd value when it exists."""
    (largest_odd, found) = main.get_largest_odd(21, 4, 17)
    assert largest_odd == 21
    assert found is True
    (largest_odd, found) = main.get_largest_odd(21, 4, 117)
    assert largest_odd == 117
    assert found is True

In summary, you should implement the following functions for the compare program:

• def get_minimum(first: int, second: int, third: int) -> int
• def get_largest_odd(first: int, second: int, third: int) -> Tuple[int, bool]
• def compare(first: int = typer.Option(...), second: int = typer.Option(...), third: int = typer.Option(...)) -> None

It is worth noting that the get_largest_odd function returns two values in the form of a Tuple[int, bool]. The first of this function's output values is the int result either the largest odd number or the smallest even number. The second bool value is a Boolean flag to indicate whether it found an odd number or not. Specifically, the get_largest_odd function should return True if it found an odd number and return False otherwise.

Running Checks¶

If you study the source code in the pyproject.toml file you will see that it includes a section that specifies different executable tasks like lint. If you are in the compare directory that contains the pyproject.toml file and the poetry.lock file, the tasks in this section make it easy to run commands like poetry run task lint to automatically run all of the linters designed to check the Python source code in your program and its test suite. You can also use the command poetry run task black to confirm that your source code adheres to the industry-standard format defined by black. If it does not meet this standard, then you can run the command poetry run black compare tests or, alternatively, poetry run task fixformat, and it will reformat the Python source code!

Along with running tasks like poetry run task lint, you can leverage the relevant instructions in the technical skills to run the command gatorgrade --config config/gatorgrade.yml to check your work. If your work meets the baseline requirements and adheres to the best practices that proactive programmers adopt you will see that all the checks pass when you run gatorgrade. You can study the config/gatorgrade.yml file in your repository to learn how the GatorGrade program runs GatorGrader to automatically check your program and technical writing.

If your program has all of the anticipated functionality, you can run the command poetry run task test and see that the test suite passes and produces output as shown in the following output. Can you think of any additional tests to add to the test suite? If you can, then add them so that you can increase your confident in program correctness!

collected 4 items

tests/test_compare.py ....

Project Reflection¶

Once you have finished all of the previous technical tasks, you can use a text editor to answer all of the questions in the writing/reflection.md file. For instance, you should provide the output of the Python program in a fenced code block, explain the meaning of the Python source code segments that you implemented and tested, compare and contrast different implementations of the Python function called get_largest_odd, and answer all of the other questions about your experiences in completing this project.

Project Assessment¶

Since this is a programming project, it is aligned with the applying and analyzing levels of Bloom's taxonomy. You can learn more about how a proactive programming expert will assess your work by examining the assessment strategy. From the start to the end of this project you may make an unlimited number of reattempts at submitting source code and technical writing that meet all aspects of the project's specification.

Seeking Assistance¶

Emerging proactive programmers who have questions about this project are invited to ask them in either the GitHub discussions forum or the Proactive Programmers Discord server. Before you ask your question, please read the advice concerning how to best participate in the Proactive Programmers community. If you find a mistake in this project, please describe it and propose a solution by creating an issue in the GitHub Issue Tracker.