Get the Fractional and Integer Parts in Python: math.modf()

The math.modf() function allows you to get both the fractional and integer parts of a number simultaneously.

• math.modf() — Mathematical functions — Python 3.11.3 documentation

For a function that returns the quotient and remainder, check out the following article on divmod().

• Get quotient and remainder with divmod() in Python

Get fractional and integer parts using math.modf()

The math.modf() function enables you to get both the fractional and integer parts of a number at once.

math.modf() returns a tuple in the format (fractional part, integer part).

import math

print(math.modf(1.5))
print(type(math.modf(1.5)))
# (0.5, 1.0)
# <class 'tuple'>

You can assign each part to a variable using unpacking. Both the fractional and integer parts are of the float data type.

• Unpack a tuple and list in Python

f, i = math.modf(1.5)

print(i)
print(f)
# 1.0
# 0.5

print(type(i))
print(type(f))
# <class 'float'>
# <class 'float'>

The sign of the parts will match that of the original value.

f, i = math.modf(-1.5)

print(i)
print(f)
# -1.0
# -0.5

math.modf() can also be applied to the int. Again, both the fractional and integer parts are float.

f, i = math.modf(100)

print(i)
print(f)
# 100.0
# 0.0

To check if a float is an integer (meaning the fractional part is 0), you can use the is_integer() method for float without obtaining the fractional part. See the following article for more information.

• Check if a number is integer or decimal in Python

Get fractional and integer parts without math module

By applying int() to a floating-point number, you can get its integer part. Consequently, you can extract both the fractional and integer parts.

• Round up/down after the decimal point in Python (math.floor, ceil)

a = 1.5

i = int(a)
f = a - int(a)

print(i)
print(f)
# 1
# 0.5

print(type(i))
print(type(f))
# <class 'int'>
# <class 'float'>