What is Data Structure?
Data Structure is a data storage format that allows for the efficient access and manipulation of the stored data. If the data is stored in a structured format, then it would be easy for a programming language to deal with it like accessing, searching, manipulating, etc.
In Python, the basic data structures include lists, sets, tuples, and dictionaries. Each of the data structures is unique in its own way. We will see all of them one by one.
Different Data Structures in Python
List
Lists are one of the simple and most commonly used data structures provided in python. It can store multiple data types at the same time like string, int, boolean, etc, and hence it is called heterogeneous.
Lists are mutable which means the data inside the list can be altered. Lists contain ordered data and can also contain duplicate values.
- Heterogeneous
- Mutable
- Ordered
- Can have duplicate value
Eg: mylist = [45, 37, ‘ABC’, 56, 89]
Tuple
Tuples are just like lists except that they are immutable which means data inside a tuple can only be accessed but cannot be altered.
- Heterogeneous
- Immutable
- Ordered
- Can have duplicate values
Eg: mytuple = (25, 30, 35, 40)
Set
Set is another data structure that holds a collection of unordered, iterable, and mutable data. But it only contains unique elements. They can contain multiple data types and hence are heterogeneous.
- Heterogeneous
- Mutable
- Unordered
Eg: myset = {“US”, “UK”, “Canada”}
Dictionary
It is slightly different from other data structures in which data are stored in the form of key-value pairs. Keys inside the dictionaries should be unique whereas their value(s) need not necessarily be unique. Any data inside the dictionary can be accessed through its key.
- Heterogeneous
- Mutable
- Unordered before Python v3.7, Ordered in Python v3.7 or more
- Do not allow duplicate values
Eg: myDictionary ={“brand”:“Ford”, “model”:“Mustang”, “year”:1964}
Working with Lists
There are lots of operations you can do with a list. As told above, a list is mutable, so you not just can access its data but also manipulate it. Let’s see it:
a) Creating a list and printing its data
mylist = ["Python", "Javascript", "HTML"]print(mylist)#Output: ["Python", "Javascript", "HTML"]mylist = ["Python", "Javascript", "HTML", "Python", "HTML"]print(mylist)#Output: ["Python", "Javascript", "HTML", "Python", "HTML"]# As you can see it allows duplicate valuesb) List length
To determine how many items a list has, thelen()function is used.
mylist = ["Audi", "Mercedes", "Rolls Royce"]print(len(mylist))#Output: 3c) Accessing Items on a list
As lists are iterable, we can access any element(s) of a list through its index value. In Python, counting starts from 0. So to get the first element of the list we use the index 0 so on and so forth.
list = ["HTML", 30, "Days", "Learning"]print(list[0])#Output: HTMLprint(list[1])#Output: 30print(list[3])#Output: LearningAccessing list items in a custom way
Getting from the last:
mylist = ["US", "Canada", "UK", "Mexico"]print(mylist[-1])#Output: MexicoWill return the third, fourth, and fifth items:
mylist = ["US", "Canada", "UK", "Mexico", "France", "Germany", "Italy"]print(mylist[2:5])#Output: ["UK", "Mexico", "France"]Returning items from the beginning to a certain point: This excludes the last point
mylist = ["US", "Canada", "UK", "Mexico", "France", "Germany", "Italy"]print(mylist[:5])#Output: ["US", "Canada", "UK", "Mexico", "France"]Returning items from a certain point to the last:
mylist = ["US", "Canada", "UK", "Mexico", "France", "Germany", "Italy"]print(mylist[3:])#Output: ["Mexico", "France", "Germany", "Italy"]d) Changing list items
Changing one value with another value:
mylist = ["US", "Canada", "UK"]mylist[1] = "Mexico"print(mylist)#Output: ["US", "Mexico", "UK"]Changing multiple values with multiple values:
mylist = ["US", "Canada", "UK", "Spain"]mylist[1:3] = ["Mexico", "Brazil"]print(mylist)#Output: ["US", "Mexico", "Brazil", "Spain"]Changing one value with two new values:
mylist = ["US", "Canada", "UK", "Spain"]mylist[1:2] = ["Mexico", "Brazil"]print(mylist)#Output: ["US", "Mexico", "Brazil", "UK", "Spain"]Changing two values with one new value:
mylist = ["US", "Canada", "UK", "Spain"]mylist[1:3] = ["Mexico"]print(mylist)#Output: ["US", "Mexico", "Spain"]e) Adding items to a list
We can add new items to a list either at the last or at any position. To insert an item in the last position of a list we use the ‘append()’ function and to insert a new item at a particular position in a list, we use the ‘insert()’ function. See the example below:
mylist = ["Python", "Java", "Javascript"]mylist.append("ReactJS")print(mylist)#Output: ["Python", "Java", "Javascript", "ReactJS"]mylist = ["Python", "Java", "Javascript"]mylist.insert(1, "ReactJS")print(mylist)#Output: ["Python", "ReactJS", "Java", "Javascript"]We can also combine two listsas can be seenin below code:
mylist = ["Python", "Java", "Javascript"]yourlist = ["Laptop", "PC", "Tablet"]mylist.extend(yourlist)print(thislist)#Output: ["Python", "Java", "Javascript", "Laptop", "PC", "Tablet"]f) Removing an item from a list
Just like adding an item to a list, we can also remove it either from the last as by default or from a specified position. Items can be deleted either by using their name or through their index value. Let’s see the example below.
Remove
mylist = ["Python", "Java", "Javascript"]mylist.remove("Java")print(mylist)#Output: ["Python", "Javascript"]Pop
mylist = ["Python", "Java", "Javascript"]mylist.pop()print(mylist)#Output: ["Python", "Java"]#Pop removes an item from the last by defaultmylist.pop(1)print(mylist)#Output: ["Python", "Javascript"]Del
mylist = ["PC", "Mobile", "Tablet"]del mylist[0]print(mylist)#Output: ["Mobile", "Tablet"]del mylist#Output: Will delete the whole listg) Deleting the whole list or emptying its data
We can delete the whole list if needed or can just clear its data in python so easily. See the examples below:
mylist = ["PC", "Mobile", "Tablet"]del mylist#Output: Will delete the whole listmylist = ["PC", "Mobile", "Tablet"]mylist.clear()print(mylist)#Output: []Read about Python find in list
Working with Sets
a) Creating a set and printing its data
myset = {'Python','Java','React'}print(myset)#Output: Python Java Reactb) Accessing Items of a set
Since data is not in an ordered manner, you cannot access items in a set by referring to an index or a key. Instead, you can loop through the set items using aforloop:
thisset = {'Laptop','PC','Tablet'}for x in thisset: print(x)#Output: Laptop PC Tabletc) Adding an item in a set
In Python we have ‘add()’ method to do the adding the item in the set:
thisset = {'Laptop','PC','Tablet'}thisset.add('Smartphone')print(thisset)#Output: Laptop PC Tablet Smartphoned) Adding two sets
We have ‘update()‘method in Python to add items from another set into the current set:
myset = {'US','UK','Canada'}yourset = {'Australia','China'}myset.update(yourset)print(myset)#Output: US UK Canada Australia Chinae) Removing an item from a set
Using ‘remove()’ method:
thisset = {'Python', 'Java', 'MongoDB'}thisset.remove('Java')print(thisset)#Output: Python MongoDBUsing ‘pop()’ method to remove a random item from a set:
myset = {'Apple','Microsoft','Google','Facebook'}myset.pop()print(myset)f) Emptying all items from a set
To clear all the data stored in a set, we have the ‘clear()’ function in Python
myset = {'Apple','Microsoft','Google','Facebook'}myset.clear()print(myset)#Output: set()g) Deleting the whole set
The'del'keyword will delete the set completely:
myset = {'Apple','Microsoft','Google','Facebook'}del mysetprint(myset)Working with Tuples
a) Creating a tuple and printing its data
thistuple = ('Javascript','Python','ReactJS')print(thistuple)#Output: Javascript Python ReactJSb) Accessing tuple items
Since tuples are ordered, we can access any element of the tuple by calling its position:
thistuple = ('Jack','Tom','Riddle')print(thistuple[1])#Output: Tomthistuple = ('Jack','Tom','Riddle')print(thistuple[-1])#Output: Riddlec) Updating the value of the tuple
Tuples areimmutable. Once a tuple is created, you cannot change its values.If you try to change or add or delete the data of a tuple, it will throw an error.You can only access the data and nothing else. But there is a way. You can first change a tuple into a list, then perform any operation of the list and then convert back the list into the tuple. Let’s see.
Updating the tuple:
First, convert the tuple into a list and then perform updating operation.
x = ('Laptop','PC','Tablet')# Converting the tuple into a listy = list(x) y[1] = 'Smartphone'# Converting the list back into the tuplex = tuple(y)print(x)#Output: Laptop Smartphone TabletAdding an item in the tuple:
First, convert the tuple into a list and then perform adding operation.
mytuple = ('Apple','Microsoft','Google')y = list(mytuple)y.append('twitter')mytuple = tuple(y)#Output: Apple Microsoft Google TwitterRemoving an item from the tuple:
First, convert the tuple into a list and then perform the removing operation.
thistuple = ('Apple','Microsoft','Facebook')y = list(thistuple)y.remove('Microsoft')thistuple = tuple(y)#Output: Apple FacebookWorking with Dictionary
a) Creating and printing data from a dictionary
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}print(dicti)#Output: {'brand' : 'DELL', 'model' : 'XPS 15', 'price' : 2000}b) Accessing Items from a dictionary
Since data in a dictionary is stored in the form of keys and their associated values, we can access the value by referring its key:
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}x = dicti.get('price')print(x)#Output: 2000c) Updating values of a dictionary
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}dicti['price'] = 3000print(dicti)#Output: {'brand': 'dell', 'model': 'xps 15', 'price': 3000}d) Adding a new entry in a dictionary
We can easily add a new entry in a dictionary in Python. Just you have to provide the value to add with its key:
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}dicti['type'] = 'Office use'print(dicti)#Output: {'brand': 'dell', 'model': 'xps 15', 'price': 3000, 'type' : 'Office use'}e) Removing an item from a dictionary
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}dicti.pop('model')print(dicti)#Output: {'brand' : 'DELL', 'price' : 2000}f) Clearing the values of a dictionary
We can clear the whole dictionary data in Python easily with ‘clear()’ functions or can even delete the whole dictionary.
Clearing the values:
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}dicti.clear()print(dicti)#Output: {}Deleting the whole dictionary:
dicti = { 'brand': 'DELL', 'model': 'XPS 15', 'price': 2000}del dictiRelated:
Python Basics
List, Set, Tuple, and Dictionary in Python
Python Reverse List items
Python Round() Function
Python Multiline comment
Power in Python | Python pow()
Python range() Function
Square Root in Python
Python for i in range
FAQs
What is list tuple set and dictionary in Python with example? ›
A list is a collection of ordered data. A tuple is an ordered collection of data. A set is an unordered collection. A dictionary is an unordered collection of data that stores data in key-value pairs.
What is list tuples dictionaries set in Python? ›| List | Tuple | Set |
|---|---|---|
| Syntax | ||
| New Items in a list can be added using the append() method. | Tuples being immutable, contain data with which it was declared, hence no new data can be added to it | The add() method adds an element to a set. |
| NA | ||
| Deleting element | ||
In Python, list and tuple are a class of data structures that can store one or more objects or values. A list is used to store multiple items in one variable and can be created using square brackets. Similarly, tuples also can store multiple items in a single variable and can be declared using parentheses.
How many data structures are there in Python? ›Python has four main data structures split between mutable (lists, dictionaries, and sets) and immutable (tuples) types. Lists are useful to hold a heterogeneous collection of related objects.
What is data structure in Python with example? ›Data Structures are the set of data elements that produce a well-organized way of storing and organizing the data in the computer so it can be used well. For example, the data structures like Stack, Queue, Linked List, etc.
Is list a data type or data structures in Python? ›Lists are one of 4 built-in data types in Python used to store collections of data, the other 3 are Tuple, Set, and Dictionary, all with different qualities and usage.
What is the difference between list dictionary set and tuple? ›The basic difference between List, tuple, set and dictionary in python is that a list is a collection of data that has been ordered. A tuple is a data collection that is ordered. A set is a collection that is not ordered. A dictionary is an unsorted data collection that stores information in key-value pairs.
What is difference between set and dictionary in Python? ›A set also refers to a data structure of the non-homogenous type, but it stores various elements in a single row. A dictionary also refers to a data structure of the non-homogenous type that functions to store key-value pairs. It allows various duplicate elements.
What is difference between list and dictionary in Python? ›A list refers to a collection of various index value pairs like that in the case of an array in C++. A dictionary refers to a hashed structure of various pairs of keys and values.
What is a set data structure in Python? ›Set is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Tuple, and Dictionary, all with different qualities and usage. A set is a collection which is unordered, unchangeable*, and unindexed. * Note: Set items are unchangeable, but you can remove items and add new items.
What is Python list data structure? ›
A list is a data structure in Python that is a mutable, or changeable, ordered sequence of elements. Each element or value that is inside of a list is called an item. Just as strings are defined as characters between quotes, lists are defined by having values between square brackets [ ] .
What is the data structure of a dictionary in Python? ›The dictionary Data Structure in Python is an unordered collection of items. While other Data Structures use only one value as the element, the dictionary is a slightly more compound data structure. It makes use of two elements i.e. a pair of elements, namely, a key and a value.
What are the four main data structures in Python? ›Python data structures are essentially containers for different kinds of data. The four main types are lists, sets, tuples and dictionaries.
What is the most basic data structure in Python? ›Summary. Lists, sets, and tuples are the basic data structures in the Python programming language.
What are the 5 programming structure of Python? ›The 5 Most Common Python Data Structures Every Programmer Should Know. In this article, we'll discuss the built-in Python data structures, which are: list, tuple, set, frozenset, and dictionary.
What is an example of a list data structure? ›A list is an ordered data structure with elements separated by a comma and enclosed within square brackets. For example, list1 and list2 shown below contains a single type of data. Here, list1 has integers while list2 has strings. Lists can also store mixed data types as shown in the list3 here.
What is simple example of data structure? ›Some examples of Data Structures are Arrays, Linked Lists, Stack, Queue, Trees, etc. Data Structures are widely used in almost every aspect of Computer Science, i.e., Compiler Design, Operating Systems, Graphics, Artificial Intelligence, and many more.
What is a tuple in Python with example? ›A tuple is an immutable object, which means it cannot be changed, and we use it to represent fixed collections of items. Let's take a look at some examples of Python tuples: () — an empty tuple. (1.0, 9.9, 10) — a tuple containing three numeric objects.
What is the difference between a tuple and a dictionary in Python? ›Differences between a tuple and a dictionary
A tuple is a non-homogeneous data structure that can hold a single row as well as several rows and columns. Dictionary is a non-homogeneous data structure that contains key-value pairs. Tuples are represented by brackets (). Dictionaries are represented by curly brackets {}.
List and tuple is an ordered collection of items. Dictionary is unordered collection. List and dictionary objects are mutable i.e. it is possible to add new item or delete and item from it. Tuple is an immutable object.
Why use a tuple instead of a list? ›
The key difference between tuples and lists is that while tuples are immutable objects, lists are mutable. This means tuples cannot be changed while lists can be modified. Tuples are also more memory efficient than the lists.
Which is faster set or dictionary in Python? ›Lookups are faster in dictionaries because Python implements them using hash tables. If we explain the difference by Big O concepts, dictionaries have constant time complexity, O(1) while lists have linear time complexity, O(n).
Why use a set instead of a dictionary? ›A set and a dictionary are basically the same, the only difference is that a set has no key-value pairing and is a series of disordered and unique element combinations. We can also use the function get(key, default) . If the key does not exist, function get() returns a default value.
What is the difference between list and tuple with example? ›The length of a tuple is fixed, whereas the length of a list is variable. Therefore, lists can have a different sizes, but tuples cannot. Tuples are allocated large blocks of memory with lower overhead than lists because they are immutable; whereas for lists, small memory blocks are allocated.
What's the primary difference between a dictionary and a list? ›But what's the difference between lists and dictionaries? A list is an ordered sequence of objects, whereas dictionaries are unordered sets. However, the main difference is that items in dictionaries are accessed via keys and not via their position.
What is the difference between array and dictionary in Python? ›An array is just a sorted list of objects. A dictionary stores key-value pairs. There are no advantages or disadvantages, they are just two data structures, and you use the one you need.
Is a list mutable or immutable? ›The list is a data type that is mutable. Once a list has been created: Elements can be modified. Individual values can be replaced.
What is a tuple in Python? ›Tuple. Tuples are used to store multiple items in a single variable. Tuple is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Set, and Dictionary, all with different qualities and usage. A tuple is a collection which is ordered and unchangeable.
What is a set data structure used for? ›A set is a data structure that can store any number of unique values in any order you so wish. Set's are different from arrays in the sense that they only allow non-repeated, unique values within them.
Where is set data structure used? ›A Set data structure allows to add data to a container, a collection of objects or primitive types (strings, numbers or booleans), and you can think of it as a Map where values are used as map keys, with the map value always being a boolean true.
What is dictionary data in Python? ›
In Python, dictionaries are mutable data structures that allow you to store key-value pairs. Dictionary can be created using the dict() constructor or curly braces' {}'. Once you have created a dictionary, you can add, remove, or update elements using the methods dict.
What is a dictionary data structure? ›A dictionary is a general-purpose data structure for storing a group of objects. A dictionary has a set of keys and each key has a single associated value. When presented with a key, the dictionary will return the associated value.
How do you create a data dictionary structure? ›- Gather terms from different departments. ...
- Give the terms a definition. ...
- Find alignment. ...
- Get support and sign off. ...
- Centralize the document. ...
- Upkeep the data dictionary.
In mathematics, a tuple is an ordered sequence of values. The values can be repeated, but their number is always finite. A tuple is often represented by a comma-delimited list whose values are enclosed in parentheses, although they're sometimes enclosed in square brackets or angle brackets.
How many types of data structures are there? ›The four basic data structure types are linear data structures, tree data structures, hash data structures and graph data structures.
What are the five Python data types and explain the data types? ›| Data Types | Classes | Description |
|---|---|---|
| Numeric | int, float, complex | holds numeric values |
| String | str | holds sequence of characters |
| Sequence | list, tuple, range | holds collection of items |
| Mapping | dict | holds data in key-value pair form |
SQLite. SQLite is probably the most straightforward database to connect to with a Python application since you don't need to install any external Python SQL modules to do so. By default, your Python installation contains a Python SQL library named sqlite3 that you can use to interact with an SQLite database.
What is stack in Python? ›A stack is a linear data structure that stores items in a Last In First Out way. In stack, elements are added at one end and an element is deleted from that end only. The insert and delete operations are called push and pop operations.
What are the three most common data types used in Python? ›You'll learn about several basic numeric, string, and Boolean types that are built into Python.
What are the 7 types of Python? ›In Python, there are seven different types of operators: arithmetic operators, assignment operators, comparison operators, logical operators, identity operators, membership operators, and boolean operators.
What is the difference between tuple list set and dictionary Python? ›
The basic difference between List, tuple, set and dictionary in python is that a list is a collection of data that has been ordered. A tuple is a data collection that is ordered. A set is a collection that is not ordered. A dictionary is an unsorted data collection that stores information in key-value pairs.
What is list and dictionary in Python with example? ›A list refers to a collection of various index value pairs like that in the case of an array in C++. A dictionary refers to a hashed structure of various pairs of keys and values. We can create a list by placing all the available elements into a [ ] and separating them using “,” commas.
What is list and tuple explain in detail with examples? ›List : A List is an ordered collection of items (which may be of same or different types) separated by comma and enclosed in square brackets. Tuple: Tuple looks similar to list. The only difference is that comma separated items of same or different type are enclosed in parentheses.
What is data structure in Python? ›The basic Python data structures in Python include list, set, tuples, and dictionary. Each of the data structures is unique in its own way. Data structures are “containers” that organize and group data according to type. The data structures differ based on mutability and order.
What is the major difference between tuples and lists in Python? ›The primary difference between tuples and lists is that tuples are immutable as opposed to lists which are mutable. Therefore, it is possible to change a list but not a tuple.
What is the difference between a set and a dictionary in Python? ›A set also refers to a data structure of the non-homogenous type, but it stores various elements in a single row. A dictionary also refers to a data structure of the non-homogenous type that functions to store key-value pairs. It allows various duplicate elements.
What is list in Python with real life example? ›List in Python is created by enclosing the list items within square brackets with the individual items separated by commas. For example, you want to create a list to store the first five even natural numbers. Even= [2,4,6,8,10]. Here [2,4,6,8,10] are the list items of the list named Even.
Which is better list or dictionary in Python? ›The list is an ordered collection of data, whereas the dictionaries store the data in the form of key-value pairs using the hashtable structure. Due to this, fetching the elements from the list data structure is quite complex compared to dictionaries in Python. Therefore, the dictionary is faster than a list in Python.
What are two differences between list and dictionary in Python? ›Lists are used to store the data, which should be ordered and sequential. On the other hand, dictionary is used to store large amounts of data for easy and quick access. List is ordered and mutable, whereas dictionaries are unordered and mutable.
What is the real life example of list and tuple? ›You can use a List to store the steps necessary to cook a chicken, because Lists support sequential access and you can access the steps in order. You can use a Tuple to store the latitude and longitude of your home, because a tuple always has a predefined number of elements (in this specific example, two).
Where do we use tuple and list? ›
The major difference is that a list is mutable, but a tuple isn't. So, we use a list when we want to contain similar items, but use a tuple when we know what information goes into it.
What is common between list and tuple? ›- They are both considered objects in Python.
- They are containers, used to store data. That data can be of any type.
- They are both ordered and maintain that order the whole time. ...
- In both tuples and lists you can access individual items by index.
In Python, dictionaries are mutable data structures that allow you to store key-value pairs. Dictionary can be created using the dict() constructor or curly braces' {}'. Once you have created a dictionary, you can add, remove, or update elements using the methods dict. update(), dict. pop(), and dict.
What is a tuple in simple words? ›In mathematics, a tuple is an ordered sequence of values. The values can be repeated, but their number is always finite. A tuple is often represented by a comma-delimited list whose values are enclosed in parentheses, although they're sometimes enclosed in square brackets or angle brackets.
How to create a set Python? ›Create a Set in Python
In Python, we create sets by placing all the elements inside curly braces {} , separated by comma. A set can have any number of items and they may be of different types (integer, float, tuple, string etc.). But a set cannot have mutable elements like lists, sets or dictionaries as its elements.