If you interested to learn about the Python variables
Data types are the classification or categorization of data items. It represents the kind of value that tells what operations can be performed on a particular data. Since everything is an object in Python programming, data types are actually classes and variables are instance (object) of these classes.
Built-in Data Types
In programming, data type is an important concept. Variables can store data of different types, and different types can do different things. Python has the following data types built-in by default, in these categories:
| Text Type: | str |
| Numeric Types: | int, float, complex |
| Sequence Types: | list, tuple, range |
| Mapping Type: | dict |
| Set Types: | set, frozenset |
| Boolean Type: | bool |
| Binary Types: | bytes, bytearray, memoryview |
Getting the Data Type
You can get the data type of any object by using the type() function:
Example
Print the data type of the variable
x:x = 5 <br>print(type(x))
Setting the Data Type
In Python, the data type is set when you assign a value to a variable:
| Example | Data Type |
|---|---|
| x = “Hello World” | str |
| x = 20 | int |
| x = 20.5 | float |
| x = 1j | complex |
| x = [“apple”, “banana”, “cherry”] | list |
| x = (“apple”, “banana”, “cherry”) | tuple |
| x = range(6) | range |
| x = {“name” : “John”, “age” : 36} | dict |
| x = {“apple”, “banana”, “cherry”} | set |
| x = frozenset({“apple”, “banana”, “cherry”}) | frozenset |
| x = True | bool |
| x = b”Hello” | bytes |
| x = bytearray(5) | bytearray |
| x = memoryview(bytes(5)) | memoryview |
Setting the Specific Data Type
If you want to specify the data type, you can use the following constructor functions:
| Example | Data Type |
|---|---|
| x = str(“Hello World”) | str |
| x = int(20) | int |
| x = float(20.5) | float |
| x = complex(1j) | complex |
| x = list((“apple”, “banana”, “cherry”)) | list |
| x = tuple((“apple”, “banana”, “cherry”)) | tuple |
| x = range(6) | range |
| x = dict(name=”John”, age=36) | dict |
| x = set((“apple”, “banana”, “cherry”)) | set |
| x = frozenset((“apple”, “banana”, “cherry”)) | frozenset |
| x = bool(5) | bool |
| x = bytes(5) | bytes |
| x = bytearray(5) | bytearray |
| x = memoryview(bytes(5)) | memoryview |
Types of Data Type
Following are the standard or built-in data type of Python:
Numeric
In Python, numeric data type represent the data which has numeric value. Numeric value can be integer, floating number or even complex numbers. These values are defined as int, float and complex class in Python.
- Integers – This value is represented by int class. It contains positive or negative whole numbers (without fraction or decimal). In Python there is no limit to how long an integer value can be.
- Float – This value is represented by float class. It is a real number with floating point representation. It is specified by a decimal point. Optionally, the character e or E followed by a positive or negative integer may be appended to specify scientific notation.
- Complex Numbers – Complex number is represented by complex class. It is specified as (real part) + (imaginary part)j. For example – 2+3j
Note – type() function is used to determine the type of data type.
- Python3
# Python program to # demonstrate numeric value a = 5print("Type of a: ", type(a)) b = 5.0print("\nType of b: ", type(b)) c = 2 + 4jprint("\nType of c: ", type(c)) |
Output:
Type of a: <class 'int'>
Type of b: <class 'float'>
Type of c: <class 'complex'>
Sequence Type
In Python, sequence is the ordered collection of similar or different data types. Sequences allows to store multiple values in an organized and efficient fashion. There are several sequence types in Python –
1) String
In Python, Strings are arrays of bytes representing Unicode characters. A string is a collection of one or more characters put in a single quote, double-quote or triple quote. In python there is no character data type, a character is a string of length one. It is represented by str class.
Creating String
Strings in Python can be created using single quotes or double quotes or even triple quotes.
- Python3
# Python Program for # Creation of String # Creating a String # with single Quotes String1 = 'Welcome to the Geeks World'print("String with the use of Single Quotes: ") print(String1) # Creating a String # with double Quotes String1 = "I'm a Geek"print("\nString with the use of Double Quotes: ") print(String1) print(type(String1)) # Creating a String # with triple Quotes String1 = '''I'm a Geek and I live in a world of "Geeks"'''print("\nString with the use of Triple Quotes: ") print(String1) print(type(String1)) # Creating String with triple # Quotes allows multiple lines String1 = '''Geeks For Life'''print("\nCreating a multiline String: ") print(String1) |
Output:
String with the use of Single Quotes:
Welcome to the Geeks World
String with the use of Double Quotes:
I'm a Geek
<class 'str'>
String with the use of Triple Quotes:
I'm a Geek and I live in a world of "Geeks"
<class 'str'>
Creating a multiline String:
Geeks
For
Life
Accessing elements of String
In Python, individual characters of a String can be accessed by using the method of Indexing. Indexing allows negative address references to access characters from the back of the String, e.g. -1 refers to the last character, -2 refers to the second last character and so on.
- Python3
# Python Program to Access # characters of String String1 = "GeeksForGeeks"print("Initial String: ") print(String1) # Printing First character print("\nFirst character of String is: ") print(String1[0]) # Printing Last character print("\nLast character of String is: ") print(String1[-1]) |
Output:
Initial String:
GeeksForGeeks
First character of String is:
G
Last character of String is:
s
Note – To know more about strings, refer Python String.
2) List
Lists are just like the arrays, declared in other languages which is a ordered collection of data. It is very flexible as the items in a list do not need to be of the same type.
Creating List
Lists in Python can be created by just placing the sequence inside the square brackets[].
- Python3
# Python program to demonstrate # Creation of List # Creating a List List = [] print("Initial blank List: ") print(List) # Creating a List with # the use of a String List = [futurefundamental'] print("\nList with the use of String: ") print(List) # Creating a List with # the use of multiple values List = ["futurefundamentals", "For", "futurefundamental"] print("\nList containing multiple values: ") print(List[0]) print(List[2]) # Creating a Multi-Dimensional List # (By Nesting a list inside a List) List = [['', 'futurefundamentalsFor'], ['futurefundamentals']] print("\nMulti-Dimensional List: ") print(List) |
Output:
Initial blank List: [] List with the use of String: ['futurefundamental'] List containing multiple values: futurefundamental futurefundamental Multi-Dimensional List: [['futurefundamental', 'For'], ['futurefundamental']]
Accessing elements of List
In order to access the list items refer to the index number. Use the index operator [ ] to access an item in a list. In Python, negative sequence indexes represent positions from the end of the array. Instead of having to compute the offset as in List[len(List)-3], it is enough to just write List[-3]. Negative indexing means beginning from the end, -1 refers to the last item, -2 refers to the second-last item, etc.
- Python3
# Python program to demonstrate # accessing of element from list # Creating a List with # the use of multiple values List = ["Geeks", "For", "Geeks"] # accessing a element from the # list using index number print("Accessing element from the list") print(List[0]) print(List[2]) # accessing a element using # negative indexing print("Accessing element using negative indexing") # print the last element of list print(List[-1]) # print the third last element of list print(List[-3]) |
Output:
Accessing element from the list
Geeks
Geeks
Accessing element using negative indexing
Geeks
Geeks
Note – To know more about Lists, refer Python List.
3) Tuple
Just like list, tuple is also an ordered collection of Python objects. The only difference between tuple and list is that tuples are immutable i.e. tuples cannot be modified after it is created. It is represented by tuple class
Creating Tuple
In Python, tuples are created by placing a sequence of values separated by ‘comma’ with or without the use of parentheses for grouping of the data sequence. Tuples can contain any number of elements and of any datatype (like strings, integers, list, etc.).
Note: Tuples can also be created with a single element, but it is a bit tricky. Having one element in the parentheses is not sufficient, there must be a trailing ‘comma’ to make it a tuple.
- Python3
# Python program to demonstrate # creation of Set # Creating an empty tuple Tuple1 = () print("Initial empty Tuple: ") print (Tuple1) # Creating a Tuple with # the use of Strings Tuple1 = ('Geeks', 'For') print("\nTuple with the use of String: ") print(Tuple1) # Creating a Tuple with # the use of list list1 = [1, 2, 4, 5, 6] print("\nTuple using List: ") print(tuple(list1)) # Creating a Tuple with the # use of built-in function Tuple1 = tuple('Geeks') print("\nTuple with the use of function: ") print(Tuple1) # Creating a Tuple # with nested tuples Tuple1 = (0, 1, 2, 3) Tuple2 = ('python', 'geek') Tuple3 = (Tuple1, Tuple2) print("\nTuple with nested tuples: ") print(Tuple3) |
Output:
Initial empty Tuple:
()
Tuple with the use of String:
('Geeks', 'For')
Tuple using List:
(1, 2, 4, 5, 6)
Tuple with the use of function:
('G', 'e', 'e', 'k', 's')
Tuple with nested tuples:
((0, 1, 2, 3), ('python', 'geek'))
Note – Creation of Python tuple without the use of parentheses is known as Tuple Packing.
Accessing elements of Tuple
In order to access the tuple items refer to the index number. Use the index operator [ ] to access an item in a tuple. The index must be an integer. Nested tuples are accessed using nested indexing.
- Python3
# Python program to # demonstrate accessing tuple tuple1 = tuple([1, 2, 3, 4, 5]) # Accessing element using indexingprint("First element of tuple")print(tuple1[0]) # Accessing element from last# negative indexingprint("\nLast element of tuple")print(tuple1[-1]) print("\nThird last element of tuple")print(tuple1[-3]) |
Output:
First element of tuple
1
Last element of tuple
5
Third last element of tuple
3
Note – To know more about tuples, refer Python Tuples.
Boolean
Data type with one of the two built-in values, True or False. Boolean objects that are equal to True are truthy (true), and those equal to False are falsy (false). But non-Boolean objects can be evaluated in Boolean context as well and determined to be true or false. It is denoted by the class bool.
Note – True and False with capital ‘T’ and ‘F’ are valid booleans otherwise python will throw an error.
- Python3
# Python program to # demonstrate boolean type print(type(True))print(type(False)) print(type(true)) |
Output:
<class 'bool'>
<class 'bool'>
Traceback (most recent call last):
File "/futurefundamentals.py", line 8, in
print(type(true))
NameError: name 'true' is not defined
Set
In Python, Set is an unordered collection of data type that is iterable, mutable and has no duplicate elements. The order of elements in a set is undefined though it may consist of various elements.
Creating Sets
Sets can be created by using the built-in set() function with an iterable object or a sequence by placing the sequence inside curly braces, separated by ‘comma’. Type of elements in a set need not be the same, various mixed-up data type values can also be passed to the set.
- Python3
# Python program to demonstrate # Creation of Set in Python # Creating a Set set1 = set() print("Initial blank Set: ") print(set1) # Creating a Set with # the use of a String set1 = set("futurefundamentals") print("\nSet with the use of String: ") print(set1) # Creating a Set with # the use of a List set1 = set(["futurefundamentals", "For", "futurefundamentals"]) print("\nSet with the use of List: ") print(set1) # Creating a Set with # a mixed type of values # (Having numbers and strings) set1 = set([1, 2, 'Geeks', 4, 'For', 6, 'futurefundamentals']) print("\nSet with the use of Mixed Values") print(set1) |
Output:
Initial blank Set:
set()
set with the use of String:
{'F', 'o', 'G', 's', 'r', 'k', 'e'}
Set with the use of List:
{'futurefundamentals', 'For'}
Set with the use of Mixed Values
{1, 2, 4, 6, 'Geeks', 'For'}
Accessing elements of Sets
Set items cannot be accessed by referring to an index, since sets are unordered the items has no index. But you can loop through the set items using a for loop, or ask if a specified value is present in a set, by using the in keyword.
- Python3
# Python program to demonstrate # Accessing of elements in a set # Creating a set set1 = set(["futurefundamentals", "For", "futurefundamentals"]) print("\nInitial set") print(set1) # Accessing element using # for loop print("\nElements of set: ") for i in set1: print(i, end =" ") # Checking the element # using in keyword print("Geeks" in set1) |
Output:
Initial set:
{'futurefundamentals', 'For'}
Elements of set:
futurefundamentals For
True
Note – To know more about sets, refer Python Sets.
Dictionary
Dictionary in Python is an unordered collection of data values, used to store data values like a map, which unlike other Data Types that hold only single value as an element, Dictionary holds key:value pair. Key-value is provided in the dictionary to make it more optimized. Each key-value pair in a Dictionary is separated by a colon :, whereas each key is separated by a ‘comma’.
Creating Dictionary
In Python, a Dictionary can be created by placing a sequence of elements within curly {} braces, separated by ‘comma’. Values in a dictionary can be of any datatype and can be duplicated, whereas keys can’t be repeated and must be immutable. Dictionary can also be created by the built-in function dict(). An empty dictionary can be created by just placing it to curly braces{}.
Note – Dictionary keys are case sensitive, same name but different cases of Key will be treated distinctly.
