Formatting Floating-Point Numbers in Python

It sounds like you’re knee-deep in the formatting jungle of floating-point numbers in Python! Totally get where you’re coming from; it can be a bit of a headache trying to display these numbers in a way that looks decent and makes sense.

Getting Started with Formatting

For basic formatting, you’ve got a couple of handy tools at your disposal:

• Using f-strings: If you’re on Python 3.6 or later, f-strings are super clean and readable.
• Using the format() function: This is a classic method that still works like a charm!

Basic Examples

Here’s a quick snapshot on how you might format your numbers:

# Using f-strings
price = 12.34567
formatted_price = f"{price:.2f}"  # Rounds to 2 decimal places
print(formatted_price)  # Output: 12.35

# Using format()
measurement = 0.123456789
formatted_measurement = "{:.4f}".format(measurement)  # Rounds to 4 decimal places
print(formatted_measurement)  # Output: 0.1235
    

When to Use Scientific Notation

Scientific notation definitely has its place—especially when you’re dealing with really small or large numbers. A good rule of thumb is to use it when you’re dealing with numbers outside the range of -1,000 to 1,000:

large_value = 123456789
formatted_large = f"{large_value:.2e}"  # Result: 1.23e+08
print(formatted_large)

small_value = 0.00001234
formatted_small = f"{small_value:.2e}"  # Result: 1.23e-05
print(formatted_small)
    

Creating a Custom Formatting Function

If you want to keep things neat, why not wrap your formatting logic into a function? This way, you can set your precision based on what you’re working with:

def format_number(value, context='general'):
    if context == 'money':
        return f"{value:.2f}"
    elif context == 'measurement':
        return f"{value:.4f}"
    elif context == 'scientific':
        return f"{value:.2e}"
    else:
        return f"{value:.2f}"  # default

# Example usage
print(format_number(12.34567, 'money'))       # 12.35
print(format_number(123456.789, 'scientific')) # 1.23e+05
    

Final Thoughts

Experiment with these examples and tweak them according to what you need! It’s all about making your data look clean and readable without sacrificing too much precision. Happy coding!