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Inbuilt Data Structures in Python
  • Last Updated : 04 Feb, 2021

Python has four basic inbuilt data structures namely Lists, Dictionary, Tuple and Set. These almost cover 80% of the our real world data structures. This article will cover the above mentioned topics. 

Above mentioned topics are divided into four sections below. 

Lists: Lists in Python are one of the most versatile collection object types available. The other two types are dictionaries and tuples, but they are really more like variations of lists.

  • Python lists do the work of most of the collection data structures found in other languages and since they are built-in, you don’t have to worry about manually creating them.
  • Lists can be used for any type of object, from numbers and strings to more lists.
  • They are accessed just like strings (e.g. slicing and concatenation) so they are simple to use and they’re variable length, i.e. they grow and shrink automatically as they’re used.
  • In reality, Python lists are C arrays inside the Python interpreter and act just like an array of pointers.

Dictionary: In python, dictionary is similar to hash or maps in other languages. It consists of key value pairs. The value can be accessed by unique key in the dictionary. 

  • Keys are unique & immutable objects.

Syntax: 



dictionary = {"key name": value}

Tuple : Python tuples work exactly like Python lists except they are immutable, i.e. they can’t be 
changed in place. They are normally written inside parentheses to distinguish them from lists (which use square brackets), but as you’ll see, parentheses aren’t always necessary. Since tuples are immutable, their length is fixed. To grow or shrink a tuple, a new tuple must be created. 

Here’s a list of commonly used tuples:

() An empty tuple
t1 = (0, ) A one-item tuple (not an expression)
t2 = (0, 1, 2, 3) A four-item tuple
t3 = 0, 1, 2, 3 Another four-item tuple (same as prior line, just minus the parenthesis)
t3 = (‘abc’, (‘def’, ‘ghi’)) Nested tuples
t1[n], t3[n][j] Index
t1[i:j], Slice
len(tl) Length

Python3




# Python program to illustrate
# tuple
tup = (1, "a", "string", 1+2)
print (tup)
print (tup[1])

Output: 

(1, 'a', 'string', 3)
a

Detailed article on Tuples in Python

Sets: Unordered collection of unique objects. 

  • Set operations such as union (|) , intersection(&), difference(-) can be applied on a set.
  • Frozen Sets are immutable i.e once created further data can’t be added to them
  • {} are used to represent a set.Objects placed inside these brackets would be treated as a set.

Python




# Python program to demonstrate working of
# Set in Python
 
# Creating two sets
set1 = set()
set2 = set()
 
# Adding elements to set1
for i in range(1, 6):
    set1.add(i)
 
# Adding elements to set2
for i in range(3, 8):
    set2.add(i)
 
print("Set1 = ", set1)
print("Set2 = ", set2)
print("\n")

Output:

('Set1 = ', set([1, 2, 3, 4, 5]))
('Set2 = ', set([3, 4, 5, 6, 7]))

To read more about sets in python read our article about set by clicking here.

 Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.  

To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning – Basic Level Course

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