Split a number into integer and decimal parts in Python

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Borislav Hadzhiev

Last updated: Jul 13, 2022

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Split a number into integer and decimal parts in Python #

Use the math.modf() method to split a number into integer and decimal parts, e.g. result = math.modf(my_num). The math.modf() method returns the fractional and integer parts of the provided number.

main.py
import math my_num = 1.3588 # ✅ split number into integer and decimal parts result = math.modf(my_num) print(result) # 👉️ (0.3588, 1.0) print(result[0]) # 👉️ 0.3588 print(result[1]) # 👉️ 1.0 # ✅ unpack decimal and integer values dec, integer = result print(dec) # 👉️ 0.3588 print(integer) # 👉️ 1.0

We used the math.modf() method to split a number into integer and decimal parts.

The math.modf method returns the fractional and integer parts of the provided number.

The fractional and integer parts carry the sign of the provided number and are floats.
main.py
import math my_num = -1.3588 result = math.modf(my_num) print(result) # 👉️ (-0.3588, -1.0) print(result[0]) # 👉️ -0.3588 print(result[1]) # 👉️ -1.0 # ✅ unpack decimal and integer values dec, integer = result print(dec) # 👉️ -0.3588 print(integer) # 👉️ -1.0

Notice that both of the values in the tuple are floats.

If you need to convert the second tuple element to an integer, use the int() class.

main.py
import math my_num = 1.3588 result = math.modf(my_num) print(result) # 👉️ (0.3588, 1.0) dec = result[0] print(dec) # 👉️ 0.3588 integer = int(result[1]) print(integer) # 👉️ 1

Alternatively, you can use the % operator and floor division //.

To split a number into integer and decimal parts:

  1. Use floor division to get the integer part of the number by dividing by 1, e.g. num // 1.
  2. Use the modulo % operator to get the fractional part by getting the remainder after dividing by 1, e.g. num % 1.
main.py
my_num = -1.3588 dec = my_num % 1 print(dec) # 👉️ 0.3588 integer = my_num // 1 print(integer) # 👉️ 1.0

The modulo (%) operator returns the remainder from the division of the first value by the second.

When we use the modulo operator to divide a number by 1, the remainder is the fractional part.

main.py
print(1.3588 % 1) # 👉️ 0.3588

You can use floor division to get the integer part of a number.

main.py
my_num = -1.3588 integer = my_num // 1 print(integer) # 👉️ 1.0 dec = my_num % 1 print(dec) # 👉️ 0.3588
The result of using the floor division // operator is that of a mathematical division with the floor() function applied to the result.

Dividing a number by 1 and rounding down, gives us the integer part of the number.

However, if you decide to use this approach, note that it doesn't handle negative numbers as you would expect.
main.py
my_num = -1.3588 dec = my_num % 1 print(dec) # 👉️ 0.6412 integer = my_num // 1 print(integer) # 👉️ -2.0

If you have to handle negative numbers, use the math.modf() method instead.

You might also see examples online that use the divmod() function. However, note that divmod() also doesn't handle negative numbers in a way you would expect.

main.py
my_num = 1.3588 result = divmod(my_num, 1) print(result) # 👉️ (1.0, 0.3588) integer = int(result[0]) print(integer) # 👉️ 1 dec = result[1] print(dec) # 👉️ 0.3588

The divmod function takes two numbers and returns a tuple containing 2 values:

  1. The result of dividing the first argument by the second.
  2. The remainder from dividing the first argument by the second.

However, the divmod() function also doesn't handle negative numbers in a way that suits our use case.

main.py
my_num = -1.3588 result = divmod(my_num, 1) print(result) # 👉️ (-2.0, 0.6412) integer = int(result[0]) print(integer) # 👉️ -2 dec = result[1] print(dec) # 👉️ 0.6412

For this reason, you should use the math.modf() method when you have to split a number into integer and decimal parts.

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