Precision handling in Python

Python's ability to control printed numerical value precision is essential for a number of uses, including financial reporting and scientific computations. Errors and misunderstandings can be avoided by accurately representing floating-point values, particularly in disciplines like data science and engineering that need extreme precision. This response examines the various ways that Python may be used to efficiently format and round numbers so that you can display data in an understandable and efficient way. Learning these strategies can improve the readability and dependability of your output, making your work more reliable and professional whether you're working with big datasets or complex calculations.

Handling precision while printing

Printing in Python isn't just about displaying data on the screen; it's about presenting it accurately and with the required precision. If you print a float point value in Python, it can print it with a precision of up to 17 significant figures. The code in the widget below attempts to print the value of $\pi$ in Python. Press the 'Run' button and see to how precision Python can display float point values.

We don't often need to print data with such high precision, and it bloats the output screen in most cases. Thankfully, Python gives us quite a few options to control the print precision of our output according to our needs. Let's explore some of these methods in this answer.

What is print precision?

Print precision refers to the control over how numerical values are displayed when printed to the console or written to a file. It's particularly relevant when dealing with floating-point numbers, where rounding errors can occur and affect the accuracy of the displayed value.

Using format specifier

Python offers several methods to control print precision. One of the most commonly used methods is through format specifiers, which allow us to specify the number of digits displayed after the decimal point.

In this example, :.2f specifies that the floating-point number should be displayed with two digits after the decimal point.

Using the % operator

We can also control print precision using the % operator. Here is some code that demonstrates its use.

The last line instructs Python to print the number stored in x with a four decimal place precision.

Using the round() function

Another approach to control precision is by using the round() function. This function allows us to round a floating-point number to a specified number of digits.

Here, round(x, 2) rounds the value of x to three decimal places.

Conclusion

Whether we're formatting floating-point numbers or rounding values, Python provides powerful tools to control precision and enhance the clarity of the output. By leveraging format specifiers, the % operator, and the round() function, we can ensure that your printed output is properly formatted.

Test yourself