float

>>> dir(float)
['__abs__', '__add__', '__bool__', '__ceil__', '__class__', '__delattr__', '__dir__', '__divmod__', '__doc__', '__eq__', '__float__', '__floor__', '__floordiv__', '__format__', '__ge__', '__getattribute__', '__getformat__', '__getnewargs__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__int__', '__le__', '__lt__', '__mod__', '__mul__', '__ne__', '__neg__', '__new__', '__pos__', '__pow__', '__radd__', '__rdivmod__', '__reduce__', '__reduce_ex__', '__repr__', '__rfloordiv__', '__rmod__', '__rmul__', '__round__', '__rpow__', '__rsub__', '__rtruediv__', '__setattr__', '__setformat__', '__sizeof__', '__str__', '__sub__', '__subclasshook__', '__truediv__', '__trunc__', 'as_integer_ratio', 'conjugate', 'fromhex', 'hex', 'imag', 'is_integer', 'real']

Definition

A float is a positive or negative number, or zero, with a foating point attached to the end. If the number doesn't have a floating point then it is a int. An operation between a float and an int will result in a float, even if the result is a whole number.

>>> type(42.0)
<class 'float'>

>>> type(42.)
<class 'float'>

>>> type(42)
<class 'int'>

Basic operations on floats

Arithmetic operations

# addition
>>> 10.3 + 3
13.3

# subraction
>>> 10.3 - 3.3
7.0

# multiplication
>>> 7.5*3.8
28.5

# division
>>> 13.86/4.2
3.3

# floor division
>>> 10 // 3
3

# modulus
>>> 10 % 3
1

# exponent
>>> 10 ** 3
1000

Incrementing and immutability

Integers can be incremented by any artimetic operator. However, since integers are immutable a variable must be used to use these incrementing operations.

>>> a = 5
>>> a += 3    # 8
>>> a *= 3    # 24
>>> a **= 2   # 576
>>> a %=6     # 0

>>> 5 *= 2
  File "<stdin>", line 1
    5 *= 2
    ^
SyntaxError: 'literal' is an illegal expression for augmented assignment

Comparison operations

Comparison operations return a boolean value.

# check equality
>>> 5.5 == 8.6
False

# check not equal to
>>> 5.5 != 8.6
True

# greater than
>>> 5.5 > 8.6
False

# less than
>>> 5.5 < 8.6
True

# greater than or equal to
>>> 5.5 >= 8.6
False

# less than or equal to
>>> 5.5 <= 8.6
True

Boolean values

All integers have truthy boolean values except for 0 which has a falsy value.

>>> bool(1.2)
True

>>> bool(-5.0)
True

>>> bool(-0.1)
True

>>> bool(0.0)
False

Readability

Underscores can be added to integers to improve their readability. This does not affect the value of the integer.

>>> 1_000.3 * 5
5001.5

>>> 1_234_567.89 + 13
1234580.89

Dunder methods

Dunder Method	Operation	Example (normal syntax)	Example (dunder call)
__add__	Addition	1.5 + 2.5 → 4.0	(1.5).__add__(2.5)
__sub__	Subtraction	3.0 - 1.0 → 2.0	(3.0).__sub__(1.0)
__mul__	Multiplication	2.0 * 4.0 → 8.0	(2.0).__mul__(4.0)
__truediv__	Division	5.0 / 2.0 → 2.5	(5.0).__truediv__(2.0)
__floordiv__	Floor division	5.0 // 2.0 → 2.0	(5.0).__floordiv__(2.0)
__mod__	Modulus	5.5 % 2.0 → 1.5	(5.5).__mod__(2.0)
__pow__	Power	2.0 ** 3.0 → 8.0	(2.0).__pow__(3.0)
__eq__	Equality	3.0 == 3.0 → True	(3.0).__eq__(3.0)
__lt__	Less than	2.0 < 5.0 → True	(2.0).__lt__(5.0)
__abs__	Absolute value	abs(-3.5) → 3.5	(-3.5).__abs__()
__round__	Rounding	round(3.5) → 4	(3.5).__round__()
__int__	Convert to int	int(3.9) → 3	(3.9).__int__()
__float__	Convert to float	float(2) → 2.0	(2).__float__()

float methods and attributes

as_integer_ratio

Returns a tuple (numerator, denominator) representing the float as an exact fraction.

>>> (5.5).as_integer_ratio()
(11, 2)

>>> (-5.5).as_integer_ratio()
(-11, 2)

---

conjugate

Returns the complex conjugate of a number. While floats don't have an complex portion the method exists for all number types.

>>> (5.5).conjugate()
5.5

---

fromhex

Returns a float from a string that represents a float. It is the inverse function of hex

>>> float.fromhex('0x1.8000000000000p+1')
3

---

hex

Returns the string representation of a float. It is the inverse function of fromhex

>>> (3.0).hex()
'0x1.8000000000000p+1'

---

imag

Returns the complex (imaginary) portion of a float. While floats don't have an complex portion the method exists for all number types.

>>> (5.3).imag
0

---

is_integer

Returns True if the value is an integer. This means that it's a float, but all characters trailing the floating point are 0. Returns False if the value is not an integer. This method performed on the int type will return an AttributeError.

>>> (5.).is_integer()
True

>>> (5.0).is_integer()
True


>>> (5.5).is_integer()
False

>>> (3.14).is_integer()
False

>>> (5).is_integer()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'int' object has no attribute 'is_integer'

---

real

Returns the real portion of an integer. While integers don't have an complex portion the method exists for all number types.

>>> (55.8).real
55.8