Data Types in Python

In Python, data types define the kind of value a variable holds. Python is dynamically typed, so you don’t have to declare the type explicitly — it’s inferred from the value you assign.

1. Numeric Types

a) Integer (int)

Whole numbers without a decimal point.

x = 10
print(type(x))  # <class 'int'>

Supports positive and negative values:

a = -5
b = 0

b) Floating-point (float)

Numbers with decimal points.

pi = 3.1415
print(type(pi))  # <class 'float'>

c) Complex (complex)

Numbers with a real and imaginary part.

z = 2 + 3j
print(type(z))  # <class 'complex'>
print(z.real)   # 2.0
print(z.imag)   # 3.0

2. Boolean Type (bool)

Represents logical values: True or False.

is_active = True
print(type(is_active))  # <class 'bool'>

print(10 > 5)  # True
print(3 == 4)  # False

3. Text Type

String (str)

Sequence of characters enclosed in quotes (single ', double ", or triple '''/""").

name = "Alice"
print(type(name))  # <class 'str'>

multiline = '''This is
a multi-line
string.'''
print(multiline)

Strings are immutable, meaning you can’t change them after creation.

4. Sequence Types

a) List (list)

Ordered, mutable collection of items.

fruits = ["apple", "banana", "cherry"]
print(type(fruits))  # <class 'list'>

fruits.append("orange")
print(fruits)  # ['apple', 'banana', 'cherry', 'orange']

print(fruits[1])  # banana

Lists can contain mixed data types:

mixed = [1, "two", 3.0, True]

b) Tuple (tuple)

Ordered, immutable collection.

coordinates = (10, 20)
print(type(coordinates))  # <class 'tuple'>

# coordinates[0] = 5  # Error! Tuples are immutable

c) Range (range)

Represents an immutable sequence of numbers, commonly used in loops.

r = range(1, 6)  # 1 to 5
print(list(r))   # [1, 2, 3, 4, 5]

5. Set Types

Set (set)

Unordered collection of unique elements.

myset = {1, 2, 3, 2, 1}
print(myset)  # {1, 2, 3}  duplicates removed

myset.add(4)
print(myset)  # {1, 2, 3, 4}

Frozen Set (frozenset)

Immutable version of set.

fs = frozenset([1, 2, 3])
# fs.add(4)  # Error! Cannot modify frozen set

6. Mapping Type

Dictionary (dict)

Key-value pairs, unordered (order preserved since Python 3.7).

person = {
    "name": "Alice",
    "age": 25,
    "city": "New York"
}
print(type(person))  # <class 'dict'>
print(person["name"])  # Alice

person["age"] = 26  # Update

7. Binary Types

• bytes: Immutable sequences of bytes.

b = b"hello"
print(type(b))  # <class 'bytes'>

• bytearray: Mutable bytes.

ba = bytearray(b"hello")
ba[0] = 72  # ASCII for 'H'
print(ba)   # bytearray(b'Hello')

Summary Table