Formatting Float Values with Python

Here are four ways to format float in Python:

Using format()
Using f-strings
Using round() function
Using the % operator

Method 1: Using format()

You can use the str.format() method to format floating-point numbers to a specific number of decimal places or in a specific format.

Visual Representation

Example 1: Formatting with two decimal places

value = 123.45678

formatted_value = "{:.2f}".format(value)

print(formatted_value)
print(type(formatted_value))

Output

123.46
<class 'str'>

The output returns a string. To convert the output to a float, use the float() function.

print(float(formatted_value))
print(type(float(formatted_value)))

Output

123.46
<class 'float'>

Example 2: Formatting with one decimal place

value = 123.45678

formatted_value = "{:.1f}".format(value)

print(float(formatted_value))

Output

123.5

Method 2: Using f-strings

Python 3.6 introduced f-strings(formatted string literals), which are a more readable and concise way to format strings compared to older methods like the % operator.

Visual Representation

Example

# Define a floating-point value
value = 123.45678

formatted_value = f"{value:.3f}"
print("Three decimals:",formatted_value)

formatted_value = f"{value:.2f}"
print("Two decimals:",formatted_value)

formatted_value = f"{value:.1f}"
print("One decimal:",formatted_value)

formatted_value = f"{value:.0f}"
print("No decimal:",formatted_value)

Output

Three decimals: 123.457
Two decimals: 123.46
One decimal: 123.5
No decimal: 123

Method 3: Using round() function

The round() function returns the floating-point number rounded off to the given digits after the decimal point.

It’s important to note that, if you want a string representation, you must convert it.

Visual Representation

Example

# Define a floating-point value
value = 123.45678

formatted_value = round(value, 3)
print("Three decimals:",formatted_value)

formatted_value = round(value, 2)
print("Two decimals:",formatted_value)

formatted_value = round(value, 1)
print("One decimal:",formatted_value)

Output

Three decimals: 123.457
Two decimals: 123.46
One decimal: 123.5

Method 4: Using the % Operator

The % operator is an older way of formatting strings and can be used for floats as well.

It works similar to format() method.

Visual Representation

Example

# Define a floating-point value
value = 123.45678

# Format the value to two decimal places
formatted_value = "%.2f" % value
print(formatted_value)

# Format the value to one decimal place
formatted_value = "%.1f" % value
print(formatted_value) 

# Format the value to no decimal places
formatted_value = "%d" % value
print(formatted_value)

Output

123.46
123.5
123

Conclusion

The format() function is versatile and can handle various formatting needs, making it suitable for complex tasks.

If you are working with 3.6+ version, it’s recommended to use f-strings due to their conciseness and readability.

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Krunal Lathiya

With a career spanning over eight years in the field of Computer Science, Krunal’s expertise is rooted in a solid foundation of hands-on experience, complemented by a continuous pursuit of knowledge.