Arithmetic Formatter

Scientific Computing with Python

Scientific Computing with Python Projects

Arithmetic Formatter

You will be working on this project with our Replit starter code.

Start by importing the project on Replit.

Next, you will see a .replit window.

Select Use run command and click the Done button.

Students in primary school often arrange arithmetic problems vertically to make them easier to solve. For example, "235 + 52" becomes:

  235

+ 52

-----

Create a function that receives a list of strings that are arithmetic problems and returns the problems arranged vertically and side-by-side. The function should optionally take a second argument. When the second argument is set to True, the answers should be displayed.

Example

Function Call:

arithmetic_arranger(["32 + 698", "3801 - 2", "45 + 43", "123 + 49"])

Output:

   32 3801 45 123

+ 698 - 2 + 43 + 49

----- ------ ---- -----

Function Call:

arithmetic_arranger(["32 + 8", "1 - 3801", "9999 + 9999", "523 - 49"], True)

Output:

  32 1 9999 523

+ 8 - 3801 + 9999 - 49

---- ------ ------ -----

  40 -3800 19998 474

Rules

The function will return the correct conversion if the supplied problems are properly formatted, otherwise, it will return a string that describes an error that is meaningful to the user.

Situations that will return an error:

If there are too many problems supplied to the function. The limit is five, anything more will return: Error: Too many problems.

The appropriate operators the function will accept are addition and subtraction. Multiplication and division will return an error. Other operators not mentioned in this bullet point will not need to be tested. The error returned will be: Error: Operator must be '+' or '-'.

Each number (operand) should only contain digits. Otherwise, the function will return: Error: Numbers must only contain digits.

Each operand (aka number on each side of the operator) has a max of four digits in width. Otherwise, the error string returned will be: Error: Numbers cannot be more than four digits.

If the user supplied the correct format of problems, the conversion you return will follow these rules:

There should be a single space between the operator and the longest of the two operands, the operator will be on the same line as the second operand, both operands will be in the same order as provided (the first will be the top one and the second will be the bottom).

Numbers should be right-aligned.

There should be four spaces between each problem.

There should be dashes at the bottom of each problem. The dashes should run along the entire length of each problem individually. (The example above shows what this should look like.)

Development

Write your code in arithmetic_arranger.py. For development, you can use main.py to test your arithmetic_arranger() function. Click the "run" button and main.py will run.

Testing

The unit tests for this project are in test_module.py. We are running the tests from test_module.py in main.py for your convenience. The tests will run automatically whenever you hit the "run" button. Alternatively you may run the tests by inputting pytest in the console.

Solution:

def arithmetic_arranger(problems, display=False):

    # Check the number of problems

    if len(problems) > 5:

        return "Error: Too many problems."

    # Initialize empty lists for components of arranged problems

    line1 = []

    line2 = []

    dashes = []

    results = []

    # Process each problem

    for problem in problems:

        num1, operator, num2 = problem.split()

        # Check the validity of the numbers and operator

        if not num1.isdigit() or not num2.isdigit():

            return "Error: Numbers must only contain digits."

        if operator not in ['+', '-']:

            return "Error: Operator must be '+' or '-'."

        # Check the number of digits in the numbers

        if len(num1) > 4 or len(num2) > 4:

            return "Error: Numbers cannot be more than four digits."

        # Calculate the result

        if operator == '+':

            result = str(int(num1) + int(num2))

        else:

            result = str(int(num1) - int(num2))

        # Determine the length of the widest operand

        width = max(len(num1), len(num2)) + 2

        # Append the components to the respective lists

        line1.append(num1.rjust(width))

        line2.append(operator + num2.rjust(width - 1))

        dashes.append('-' * width)

        results.append(result.rjust(width))

    # Combine the components into formatted strings

    arranged_problems = ' '.join(line1) + '\n' + ' '.join(line2) + '\n' + ' '.join(dashes)

    if display:

        arranged_problems += '\n' + ' '.join(results)

    return arranged_problems