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Precision Handling in Python | floor, ceil, round, trunc, format

Learn the different methods for precision handling of floating-point numbers.


Precision handling is a process of rounding off the values of floating-point numbers. Python has many built-in functions to handle the precision, like floor, ceil, round, trunc, and format. Let's discuss the different types of precision handling in Python.

Some of these methods require the math module to be imported.

floor() function in Python

The floor function returns the largest integer less than or equal to a given number. Let's take an example to understand the floor function:

import math

value = 34.185609
print(math.floor(value))
# 34

value = -34.185609
print(math.floor(value))
# -35

ceil() function in Python

The ceil function returns the smallest integer greater than or equal to a given number. Let's take an example to understand the ceil function:

import math

value = 34.185609
print(math.ceil(value)
# 35

value = -34.185609
print(math.ceil(value)
# -34

trunc() function in Python

The trunc function returns the integer part of a number by removing all the decimal parts from a floating-point number. Let's take an example to understand the trunc function:

import math

value = 34.185609
print(math.trunc(value))
# 34

value = -34.185609
print(math.trunc(value))
# -34

round() function in Python

The round function rounds off the output in a customized format. We can pass the number of decimal places as an argument, and it then rounds a number to the given precision in decimal digits. Let's take an example to understand the round function:

value = 34.185609

print(round(value, 2))
# 34.19
print(round(value, 3))
# 34.186
print(round(value, 4))
# 34.1856

Interesting fact: round() can also take a negative integer as second argument:

value = 1346.185609

print(round(value, 0))
# 1346.0
print(round(value, -1))
# 1350.0
print(round(value, -2))
# 1300.0
print(round(value, -3))
# 1000.0

Formatting with f-Strings in Python

f-Strings can be used to format values in a String:

value = 34.185609

print(f'The value is: {value:.2f}')
# The value is: 34.19
print(f'The value is: {value:.3f}')
# The value is: 34.186

format() function in Python

The format function can also be used to format the output. Let's take an example to understand the format function:

value = 34.185609

print('The value is {0:.2f}'.format(value))
# The value is 34.19

% formatting operator in Python

And similar, the % operator can be used to format and set the precision of the output:

value = 34.185609

print('The value is: %.3f' % value)
# The value is: 34.186

Conclusion

In this article, we have discussed the different types of precision handling in Python. We have also discussed the different types of formatting in Python.


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