Last updated: Oct 04, 2023

Data Types in Python

A Data type is the type of value a variable can store.

Python is a dynamically typed programming language, which means that the data type of a variable does not need to be declared. A variable data type is determined at runtime. However, you must be aware of the data types supported by Python.

Python has the following built-in data types:

Data Type	Description	Example
str	A string which is a sequence of character.	x = "Hello World"
int	Numeric value without decimal point.	a = 467
float	Numeric value with decimal point.	14.7
complex	Numeric real value with imaginary component.	x = 14j
list	Collection of ordered and mutable data. This type allows duplicate values.	x = ["apple", "grapes", "mango", "orange", "apple"]
tuple	Collection of ordered and immutable data. This type allows duplicate values.	x = ("apple", "grapes", "mango", "orange", "mango")
dict	A collection with key-value pairs which are unordered, unindexed and mutable. This type allows no duplicate keys.	a = {"name" : "Danny", "email" : "danny@tutorialsbuddy.com"}
set	A collection with unindexed and unordered values. This type allows no duplicate values.	a = {"pen", "book", "laptop"}
frozenset	A built-in function to make iterable object immutable.	frozenset({"pen", "book", "laptop"})
bytes	A byte representation of an object value.	a = b"Hello World"
bytearray	A built-in function to convert object's value into bytearray.	x = bytearray(10)
memoryview	A built-in function to convert object into memoryview object. Memoryview allows to safely access the internal buffer of an object in Python. Internal buffer refers to a physical memory storage used temporarily to store data.	x = memoryview(bytes(10))
bool	A boolean value either True or False.	x = True
range	A built-in function that generates a sequence of numbers starting with 0 by default and stops just before the specified number. It is commonly used in for loop.	for i in range(10): print(i, end = " ") print()

Declaring Data Type

Python variables don't need to have their data types declared explicitly. The data type of a variable is determined by the kind of value assigned to it.

a = "Hello World!"
print(a, " is of type ", type(a).__name__)

a = 100
print(a, " is of type ", type(a).__name__)

a = 100.34
print(a, " is of type ", type(a).__name__)

a = 100j
print(a, " is of type ", type(a).__name__)

a = [10, 45, 23, 78, 19, 20, 14]
print(a, " is of type ", type(a).__name__)

a = (100, 503, 45)
print(a, " is of type ", type(a).__name__)

a = {"name":"Danny", "age": 27}
print(a, " is of type ", type(a).__name__)

a = {"apple", "grapes", "mango"}
print(a, " is of type ", type(a).__name__)

a = frozenset({56, 22, 17})
print(a, " is of type ", type(a).__name__)

a = b"Hello world!"
print(a, " is of type ", type(a).__name__)

a = bytearray("Hello world!", "utf-8")
print(a, " is of type ", type(a).__name__)

a = memoryview(bytes("Hello world!", "utf-8"))
print(a, " is of type ", type(a).__name__)

a = True
print(a, " is of type ", type(a).__name__)

a = range(10)
print(a, " is of type ", type(a).__name__)

The output of the above code is as follows:

Hello World! is of type str
100 is of type int
100.34 is of type float
100j is of type complex
[10, 45, 23, 78, 19, 20, 14] is of type list
(100, 503, 45) is of type tuple
{'name': 'Danny', 'age': 27} is of type dict
{'mango', 'grapes', 'apple'} is of type set
frozenset({56, 17, 22}) is of type frozenset
b'Hello world!' is of type bytes
bytearray(b'Hello world!') is of type bytearray
<memory at 0x7fc3e57a5280> is of type memoryview
True is of type bool
range(0, 10) is of type range

Declaring Specific Data Type

In Python, we can also specify the data type of a variable using the constructor functions as shown in the example below:

a = str("Hello World!")

a = int(100)

a = float(100.34)

a = complex(100j)

a = list((10, 45, 23, 78, 19, 20, 14))

a = tuple((100, 503, 45))

a = dict({"name":"Danny", "age": 27})

a = set(("apple", "grapes", "mango"))

a = frozenset({56, 22, 17})

a = bytes("Hello world!", "utf-8")

a = bytearray("Hello world!", "utf-8")

a = memoryview(bytes("Hello world!", "utf-8"))

a = bool(0)

a = range(10)

Choosing the Right Data Types

The right data type for a variable not only assures that a program runs correctly, but it also improves code efficiency. If you want to add the values of two variables, then both variables must be integer. You can't expect 2 by adding 1 + "1" because 1 is an integer and "1" is a string.

The following example gives Type Error because we are attempting to add an integer and a string variable:

a = 1
b = "1"
c = a + b
print(c)

The output of the above code is as follows:

TypeError: unsupported operand type(s) for +: 'int' and 'str'

Here's an example to add two integer variables correctly in Python:

a = 1
b = 1
c = a + b
print(c)

The output of the above code is as follows:

How to find the data type of an object or a variable?

To determine the data type of an object or variable, use Python's type() function.

Here's an example to demonstrate this:

x = 67
print(type(x))

The output of the above code is as follows:

<class 'int'>