Python Data Types

In programming, data types are an important concept. Variables can store data of different types, and different types can perform different operations. Python has multiple built-in data types, mainly classified into the following categories:

Core Data Types

Type Name	Type Alias	Example	Description
Text Type	str	"Hello", 'Python'	Used to store text, composed of a series of characters.
Numeric Type	int	10, -50	Integers.
	float	3.14, -0.01	Floating point numbers (i.e., decimal).
	complex	1+2j	Complex numbers.
Sequence Type	list	[1, "apple", 3.0]	Lists, ordered and modifiable collections.
	tuple	(1, "apple", 3.0)	Tuples, ordered but immutable collections.
	range	range(6)	Represents an immutable numeric sequence.
Mapping Type	dict	{"name": "John", "age": 30}	Dictionaries, unordered key-value pair collections.
	Set Type	set	{"apple", "banana"}
	Frozen Set Type	frozenset	frozenset({"a", "b"})
Boolean Type	bool	True, False	Represents true or false.
Binary Type	bytes, bytearray, memoryview	b"Hello"	Used to process binary data.
None Type	NoneType	None	Represents an empty value or non-existent value.

Getting Variable Type

You can use the built-in type() function to check the data type of any variable.

x = 5
y = "Hello, World!"
z = [1, 2, 3]

print(type(x))  # Output: <class 'int'>
print(type(y))  # Output: <class 'str'>
print(type(z))  # Output: <class 'list'>

Python is Dynamically Typed

Python is a dynamically typed language. This means you don't need to specify the variable's type when declaring it; the interpreter automatically infers it at runtime. This makes development more flexible and fast.

my_var = 100       # At this point, my_var is int type
print(type(my_var))

my_var = "Now I'm a string"  # Now my_var has become str type
print(type(my_var))

Mutable and Immutable Types

Data types can be classified as mutable or immutable based on whether their values can be changed after creation.

• Immutable (Mutable): Once created, their values cannot be changed. If you perform a modification on a variable, it actually creates a new object.

  • Includes: int, float, complex, str, tuple, frozenset, bool, bytes

  a = "hello"
  a[0] = 'H'  # This will raise TypeError error because strings are immutable
  a = "world"   # This is not a modification, but rather lets a point to a new string object

• Mutable (Mutable): After creation, their values can be changed, without needing to create a new object.

  • Includes: list, dict, set, bytearray

  my_list = [1, 2, 3]
  my_list[0] = 99  # Modify directly on the original list
  print(my_list)   # Output: [99, 2, 3]

Understanding the difference between mutable and immutable types is crucial for writing efficient and bug-free Python code.