Python Examples

  • Online Python Compiler
  • Hello World
  • Console Operations
  • Conditional Statements
  • Loop Statements
  • Builtin Functions
  • Type Conversion

Collections

  • Classes and Objects
  • File Operations
  • Global Variables
  • Regular Expressions
  • Multi-threading
  • phonenumbers
  • Breadcrumbs
  • ► Python Examples
  • ► ► Type Conversion
  • ► ► ► Convert Python Dictionary Keys to List
  • Python Type Conversion
  • Type Conversion Tutorials
  • Convert Int to Float
  • Convert Int to Complex Number
  • Convert Int to String
  • Convert Float to Int
  • Convert Float to Complex
  • Convert Float to String
  • Convert String to Int
  • Convert String to Float
  • Convert Decimal to Hex
  • Convert Hex to Decimal
  • Convert List to Tuple
  • Convert List to Set
  • Convert Tuple to List
  • Convert Tuple to Set
  • Convert Set to List
  • Convert Set to Tuple
  • Convert Range to List

Convert Python Dictionary Keys to List

  • Convert dictionary keys to a list using dict.keys()
  • Convert dictionary keys to a list using List Comprehension
  • Convert dictionary keys to a list using For loop

Python Dictionary Keys to List

To convert Python Dictionary keys to List, you can use dict.keys() method which returns a dict_keys object. This object can be iterated, and if you pass it to list() constructor, it returns a list object with dictionary keys as elements.

A simple code snippet to convert dictionary keys to list is

1. Convert dictionary keys to a list using dict.keys()

In the following program, we have a dictionary initialized with three key:value pairs. We will use dict.keys() method to get the dict_keys object. We pass dict.keys() as argument to list() constructor. list() returns the list of keys.

Python Program

2. Convert dictionary keys to a list using List Comprehension

We can also use List Comprehension to get the keys of dictionary as elements of a list.

3. Convert dictionary keys to a list using For loop

If you are not comfortable with List comprehension, let us use For Loop. When you iterate on the dictionary, you get next key during each iteration. Define an empty list keysList to store the keys and append the key during each iteration in for loop.

In this tutorial of Python Examples , we learned how to get Dictionary keys as List.

  • Free Python 3 Tutorial
  • Control Flow
  • Exception Handling
  • Python Programs
  • Python Projects
  • Python Interview Questions
  • Python Database
  • Data Science With Python
  • Machine Learning with Python

Related Articles

  • Solve Coding Problems
  • Python Counter | Majority Element
  • Output of Python Programs | Set 24 (Dictionary)
  • Initialize an Empty Dictionary in Python
  • Python program to print the dictionary in table format
  • Python Dictionary get() Method
  • Internal Structure of Python Dictionary
  • Regular Dictionary vs Ordered Dictionary in Python
  • Convert nested Python dictionary to object
  • Merging and Updating Dictionary Operators in Python 3.9
  • Different ways of sorting Dictionary by Keys and Reverse sorting by keys
  • How to save a Python Dictionary to a CSV File?
  • How to read Dictionary from File in Python?
  • How to find length of dictionary values?
  • Python Dictionary copy()
  • Get a dictionary from an Objects Fields
  • Python Dictionary clear()
  • Python | Ways to Copy Dictionary
  • Python Dictionary Comprehension
  • Building a terminal based online dictionary with Python and bash

How to use a List as a key of a Dictionary in Python 3?

In Python, we use dictionaries to check if an item is present or not . Dictionaries use key:value pair to search if a key is present or not and if the key is present what is its value . We can use integer, string, tuples as dictionary keys but cannot use list as a key of it . The reason is explained below .

How does Python Dictionaries search their keys   

If the Python dictionaries just iterate over their keys to check if the given keys are present or not it would take O(N) time. But python dictionaries take O(1) to check if the key is present or not. So, how dictionaries search the key, for every key it generates a hash value for the key and by this hash value, it can track its elements.

Problems if lists were used as a key of dictionaries   

Lists are mutable objects which means that we can change values inside a list append or delete values of the list . So if a hash function is generated from a list and then the items of the lists changed the dictionary will generate a new hash value for this list and could not find it.

For example, If the list is a = [1, 2, 3, 4, 5] and supposes hash of a list is the sum of values inside the list. So hash(a) = 15. Now we append 6 to a . So a = [1, 2, 3, 4, 5, 6] hash(a) = 21. So hash value of a changed. Therefore it can not be found inside the dictionary.

Another problem is different lists with the same hash value. If b = [5, 5, 5] hash(b) = 15. So if a (From the above example with the same hash value) is present is inside the dictionary, and if we search for b. Then the dictionary may give us the wrong result.

How to deal with this  

We can change the list into immutable objects like string or tuple and then can use it as a key.  Below is the implementation of the approach.  

  Output:

Please Login to comment...

  • python-dict

Improve your Coding Skills with Practice

 alt=

What kind of Experience do you want to share?

Datagy logo

  • Learn Python
  • Python Lists
  • Python Dictionaries
  • Python Strings
  • Python Functions
  • Learn Pandas & NumPy
  • Pandas Tutorials
  • Numpy Tutorials
  • Learn Data Visualization
  • Python Seaborn
  • Python Matplotlib

Python: Add Key:Value Pair to Dictionary

  • December 6, 2021 December 19, 2022

How to Add Items to a Python Dictionary Cover Image

In this tutorial, you’ll learn how to add key:value pairs to Python dictionaries . You’ll learn how to do this by adding completely new items to a dictionary, adding values to existing keys, and dictionary items in a for loop, and using the zip() function to add items from multiple lists.

What are Python dictionaries? Python dictionaries are incredibly helpful data types, that represent a hash table, allowing data retrieval to be fast and efficient. They consist of key:value pairs, allowing you to search for a key and return its value. Python dictionaries are created using curly braces, {} . Their keys are required to be immutable and unique, while their values can be any data type (including other dictionaries) and do not have to be unique.

The Quick Answer: Use dict[key] = [value] to Add Items to a Python Dictionary

Quick Answer - Python Add Append Item to Dictionary

Table of Contents

Add an Item to a Python Dictionary

The easiest way to add an item to a Python dictionary is simply to assign a value to a new key. Python dictionaries don’t have a method by which to append a new key:value pair. Because of this, direct assignment is the primary way of adding new items to a dictionary.

Let’s take a look at how we can add an item to a dictionary:

We can see here that we were able to easily append a new key:value pair to a dictionary by directly assigning a value to a key that didn’t yet exist.

What can we set as dictionary keys? It’s important to note that we can add quite a few different items as Python dictionary keys. For example, we could make our keys strings, integers, tuples – any immutable item that doesn’t already exist. We can’t, however, use mutable items (such as lists) to our dictionary keys.

In the next section, you’ll learn how to use direct assignment to update an item in a Python dictionary.

Update an Item in a Python Dictionary

Python dictionaries require their keys to be unique. Because of this, when we try to add a key:value pair to a dictionary where the key already exists, Python updates the dictionary. This may not be immediately clear, especially since Python doesn’t throw an error.

Let’s see what this looks like, when we add a key:value pair to a dictionary where the key already exists:

We can see that when we try to add an item to a dictionary when the item’s key already exists, that the dictionary simply updates. This is because Python dictionaries require the items to be unique, meaning that it can only exist once.

In the next section, you’ll learn how to use a for loop to add multiple items to a Python dictionary.

Append Multiple Items to a Python Dictionary with a For Loop

There may be times that you want to turn two lists into a Python dictionary. This can be helpful when you get data from different sources and want to combine lists into a dictionary data structure.

Let’s see how we can loop over two lists to create a dictionary:

Here, we loop over each value from 0 through to the length of the list minus 1, to access the indices of our lists. We then access the i th index of each list and assign them to the keys and values of our lists.

There is actually a much simpler way to do this – using the Python zip function, which you’ll learn about in the next section.

Add Multiple Items to a Python Dictionary with Zip

The Python zip() function allows us to iterate over two iterables sequentially . This saves us having to use an awkward range() function to access the indices of items in the lists.

Let’s see what this looks like in Python:

The benefit of this approach is that it is much more readable. Python indices can be a difficult thing for beginner Python developers to get used to. The zip function allows us to easily interpret what is going on with our code. We can use the zip function to name our iterable elements, to more easily combine two lists into a dictionary.

If you’re working with a dictionary that already exists, Python will simply update the value of the existing key. Because Python lists can contain duplicate values, it’s important to understand this behaviour. This can often lead to unexpected results since the program doesn’t actually throw an error.

In this tutorial, you learned how to use Python to add items to a dictionary. You learned how to do this using direct assignment, which can be used to add new items or update existing items. You then also learned how to add multiple items to a dictionary using both for loops and the zip function.

To learn more about Python dictionaries, check out the official documentation here .

Additional Resources

To learn more about related topics, check out the articles below:

  • Python: Pretty Print a Dict (Dictionary) – 4 Ways
  • Python: Check if a Dictionary is Empty (5 Ways!)
  • Python: Check if a Key (or Value) Exists in a Dictionary (5 Easy Ways)
  • Python: Remove Key from Dictionary (4 Different Ways)
  • Merge Python Dictionaries – 4 Different Ways

Nik Piepenbreier

Nik is the author of datagy.io and has over a decade of experience working with data analytics, data science, and Python. He specializes in teaching developers how to use Python for data science using hands-on tutorials. View Author posts

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Learn Python practically and Get Certified .

Popular Tutorials

Popular examples, reference materials, learn python interactively, python introduction.

  • Getting Started
  • Keywords and Identifier
  • Python Comments
  • Python Variables
  • Python Data Types
  • Python Type Conversion
  • Python I/O and Import
  • Python Operators
  • Python Namespace

Python Flow Control

  • Python if...else
  • Python for Loop
  • Python while Loop
  • Python break and continue
  • Python Pass

Python Functions

  • Python Function
  • Function Argument
  • Python Recursion
  • Anonymous Function
  • Global, Local and Nonlocal
  • Python Global Keyword
  • Python Modules
  • Python Package

Python Datatypes

  • Python Numbers

Python List

Python Tuple

  • Python String
  • Python Dictionary

Python Files

  • Python File Operation
  • Python Directory
  • Python Exception
  • Exception Handling
  • User-defined Exception

Python Object & Class

  • Classes & Objects
  • Python Inheritance
  • Multiple Inheritance
  • Operator Overloading

Python Advanced Topics

  • Python Iterator
  • Python Generator
  • Python Closure
  • Python Decorators
  • Python Property
  • Python RegEx
  • Python Examples

Python Date and time

  • Python datetime Module
  • Python datetime.strftime()
  • Python datetime.strptime()
  • Current date & time
  • Get current time
  • Timestamp to datetime
  • Python time Module
  • Python time.sleep()

Python Tutorials

Python List pop()

  • Python List remove()

Python List insert()

Python List index()

  • Python List append()
  • Python List copy()

Python lists store multiple data together in a single variable .

Suppose, we need to store the age of 5 students, instead of creating 5 separate variables, we can simply create a list:

List with 5 Elements

  • Create a Python List

We create a list by placing elements inside square brackets [] , separated by commas. For example,

Here, the ages list has three items.

Here are the different types of lists we can create in Python.

List of different data types

List of mixed data types

  • Access List Elements

Each element in a list is associated with a number, known as a list index .

The index always starts from 0 , meaning the first element of a list is at index 0 , the second element is at index 1, and so on.

Index of List Elements

Access Elements Using Index

We use index numbers to access list elements. For example,

Access List Elements

More on Accessing List Elements

Python also allows negative indexing. The negative index always starts from -1 , meaning the last element of a list is at index -1 , the second-last element is at index -2, and so on.

Python Negative Indexing

Negative index numbers make it easy to access list items from last.

Let's see an example,

Note : If the specified index does not exist in a list, Python throws the IndexError exception.

In Python, it is possible to access a section of items from the list using the slicing operator : . For example,

To learn more about slicing in Python, visit Python program to slice lists .

  • Add Elements to a Python List

We use the append() method to add elements to the end of a Python list. For example,

The insert() method adds an element to the specified index of the list. For example,

We use the extend() method to add elements to a list from other iterables. For example,

Here, we have added all the elements of even_numbers to odd_numbers .

  • Change List Items

We can change the items of a list by assigning new values using the = operator. For example,

Here, we have replaced the element at index 2: 'Green' with 'Blue' .

Note : Unlike Python tuples , lists are mutable, meaning we can change the items in the list.

  • Remove an Item From a List

We can remove an item from a list using the remove() method. For example,

The del statement removes one or more items from a list. For example,

Note : We can also delete the entire list by using the del statement. For example,

  • Python List Length

We use the len() method to find the number of elements present in a list. For example,

  • Iterating Through a List

We use a for loop to iterate over the elements of a list. For example,

  • Python List Methods

Python has many useful list methods that make it really easy to work with lists.

More on Python Lists

List Comprehension is a concise and elegant way to create a list. For example,

To learn more, visit Python List Comprehension .

We use the in keyword to check if an item exists in the list. For example,

  • orange is not present in fruits , so, 'orange' in fruits evaluates to False .
  • cherry is present in fruits , so, 'cherry' in fruits evaluates to True .
  • Python list()

Table of Contents

  • Introduction

Video: Python Lists and Tuples

Sorry about that.

Related Tutorials

Python Library

Python Tutorial

Effortlessly Add Keys to Python Dictionaries: A Complete Guide

add keys to dictionary python

Dictionaries are a built-in data structure in Python used for mapping keys to values. They are similar to lists, but instead of using indices to access values, you use keys. In this article, we’ll explore how to add keys to dictionary in Python and how to use them effectively in your code.

Creating a Dictionary

The syntax for creating a dictionary in Python is straightforward. You enclose a comma-separated list of key-value pairs within curly braces:

Adding Keys to a Dictionary

There are several ways to add keys to a dictionary in Python. One common method is to use square brackets and assignment:

Another way to add keys to a dictionary in Python is to use the update() method:

Updating Existing Keys

If you add a key to a dictionary that already exists, the value associated with that key will be updated:

Using the get() Method

When you’re working with dictionaries, it’s important to be able to access the values associated with specific keys. One way to do this is to use square brackets:

However, this approach can cause an error if you try to access a key that doesn’t exist in the dictionary. To avoid this, you can use the get() method instead:

The get() method takes two arguments: the first is the key you want to access, and the second is an optional default value to return if the key doesn’t exist.

Add keys to a dictionary using for loop

You can add keys to a dictionary within a loop by using the dictionary’s bracket notation to access and add items. Here’s an example:

In this example, we first define an empty dictionary called my_dict . We also define a list of keys ( keys ) and a list of values ( values ). We then loop through the keys and values using a for loop that goes through the range of the length of the keys list.

Within the loop, we use the bracket notation to access the key at the current index of the keys list ( keys[i] ) and add the corresponding value from the values list ( values[i] ) as the value for that key in the dictionary ( my_dict[keys[i]] = values[i] ).

After the loop, we print the resulting dictionary, which should contain the key-value pairs from the keys and values lists.

Add keys to dictionary if not exists

To add keys to a dictionary only if they don’t already exist, you can use the setdefault() method of the dictionary. This method sets a key to a default value if the key is not already in the dictionary. Here’s an example:

In this example, we first define a dictionary called my_dict with some initial keys and values. We also define a list of keys ( keys ) and a list of values ( values ). We then loop through the keys and values using a for loop that goes through the range of the length of the keys list.

Within the loop, we use the setdefault() method to add the key-value pair to the dictionary only if the key doesn’t already exist in the dictionary. If the key already exists, the setdefault() method returns the current value for that key without changing it.

After the loop, we print the resulting dictionary, which should contain all the original keys and values from the dictionary, as well as any new key-value pairs that were added from the keys and values lists.

Add tuple as key to dictionary

You can use a tuple as a key for a dictionary in Python. Here’s an example:

we define a dictionary called my_dict with a tuple key ('a', 1) and a corresponding value 'apple' . We can access the value for this key using the bracket notation my_dict[('a', 1)] .

To add a new key-value pair with a tuple key, we can simply use the bracket notation to assign a value to a new tuple key ('b', 2) like so: my_dict[('b', 2)] = 'banana' .

Add key to dictionary using list comprehension

You can add keys to a dictionary using a list comprehension by creating a dictionary with the key-value pairs and then using dictionary comprehension to filter and add keys to the original dictionary. Here’s an example:

In this example, we define the original dictionary my_dict , and a list of keys to add keys_to_add , and a value for the new keys value .

We create a new dictionary new_dict with the key-value pairs to add, using a dictionary comprehension to create a dictionary with keys from the keys_to_add list, and a value of value .

We then use the ** operator to unpack both dictionaries ( my_dict and new_dict ) into a new dictionary. This is done in a dictionary comprehension to add the new keys to the original dictionary and any existing keys in my_dict will be overwritten with the new value of value .

Finally, we print the updated dictionary with the new keys added.

Yes, you can add a key with multiple values to a dictionary by assigning a list or another dictionary as the value.

Yes, you can add a key with a value of any data type to a dictionary, including strings, integers, floating-point numbers, lists, dictionaries, and more.

Dictionaries are a powerful tool for mapping keys to values in Python. By adding keys to dictionaries, you can store and retrieve information in a flexible and efficient way. Whether you’re using square brackets and assignment, the update() method, or the get() method, there are many ways to work with dictionaries in Python.

It’s important to keep in mind that dictionaries are unordered, which means that the keys and values may not be stored in the order you expect. However, you can use the sorted() function to sort the keys in a dictionary, or you can use the collections module to create an ordered dictionary that preserves the order of the keys.

Whether you’re a beginner or an experienced programmer, understanding dictionaries and how to add keys to them is a valuable skill to have. Try incorporating dictionaries into your own projects, and see how they can simplify your code and improve your workflow.

Trending Python Articles

[Fixed] typeerror can’t compare datetime.datetime to datetime.date

Python: How to Add Keys to a Dictionary

python assign key to list

  • Introduction

A dictionary in Python is a collection of items that store data as key-value pairs. We can access and manipulate dictionary items based on their key. Dictionaries are mutable and allow us to add new items to them.

The quickest way to add a single item to a dictionary is by using a dictionary's index with a new key and assigning a value. For example, we add a new key-value pair like this:

Python allows adding multiple items to dictionaries as well. In this tutorial, we'll take a look at how to add keys to a dictionary in Python .

  • Add Key to a Python Dictionary

There are multiple ways to add a new key-value pair to an existing dictionary. Let's have a look at a few common ways to do so.

  • Add Key with Value

We can add a new key to a dictionary by assigning a value to it. If the key is already present, it overwrites the value it points to. The key has to be written in subscript notation to the dictionary like this:

This key-value pair will be added to the dictionary. If you're using Python 3.6 or later, it will be added as the last item of the dictionary.

Let's make a dictionary, and then add a new key-value pair with this approach:

This will result in:

  • Add Key to Dictionary without Value

If you'd just like to add a key, without a value, you can simply put None instead of the value, with any of the methods covered in this article:

This results in:

  • Add Multiple Key-Value Pairs with update()

In Python, we can add multiple key-value pairs to an existing dictionary. This is achieved by using the update() method. This method takes an argument of type dict or any iterable that has the length of two - like ((key1, value1),) , and updates the dictionary with new key-value pairs.

If the key is already present in the dictionary, it gets overwritten with the new value.

The keys can also be passed as keyword arguments to this method with their corresponding values, like dictionary.update(new_key=new_value) .

Note: This is arguably the most popular method of adding new keys and values to a dictionary.

Let's use the update() method to add multiple key-value pairs to a dictionary:

Running this code will produce the following output:

  • Using Merge Operator (Python 3.9+)

From Python version 3.9, Merge ( | ) and Update ( |= ) operators have been added to the built-in dict class.

These are very convenient methods to add multiple key-value pairs to a dictionary. The Merge ( | ) operator creates a new dictionary with the keys and values of both of the given dictionaries. We can then assign this result to a new dictionary.

Check out our hands-on, practical guide to learning Git, with best-practices, industry-accepted standards, and included cheat sheet. Stop Googling Git commands and actually learn it!

Whereas the Update ( |= ) operator, adds the key-value pairs of the second dictionary into the first dictionary. So, the existing dictionary gets updated with multiple key-value pairs from another dictionary.

Here's an example of using Merge ( | ) and Update ( |= ) operators to add new keys to a dictionary:

This code will produce the following output on the Python(3.9+) interpreter:

In this tutorial, we learned how we can add a new key to a dictionary. We first added the key-value pair using subscript notation - we added a key to a dictionary by assigning a value to it. We then looked at the update() method to add multiple key-value pairs to a dictionary. We've also used the update() method with parameters of type dictionary, tuple, and keyword arguments. Lastly, we probed into the Merge and Update operators available from Python versions 3.9 onwards.

The update() method of dictionary proves to be the most popular way to add new keys to an existing dictionary.

You might also like...

  • Guide to Hash Tables in Python
  • Dictionaries vs Arrays in Python - Deep Dive
  • Modified Preorder Tree Traversal in Django
  • Stacks and Queues in Python
  • Python Performance Optimization

Improve your dev skills!

Get tutorials, guides, and dev jobs in your inbox.

No spam ever. Unsubscribe at any time. Read our Privacy Policy.

Freelance Python Developer

In this article

python assign key to list

Graphs in Python - Theory and Implementation

Graphs are an extremely versatile data structure. More so than most people realize! Graphs can be used to model practically anything, given their nature of...

David Landup

Data Visualization in Python with Matplotlib and Pandas

Data Visualization in Python with Matplotlib and Pandas is a course designed to take absolute beginners to Pandas and Matplotlib, with basic Python knowledge, and...

© 2013- 2024 Stack Abuse. All rights reserved.

Assign a dictionary Key or Value to variable in Python

avatar

Last updated: Feb 21, 2023 Reading time · 4 min

banner

# Table of Contents

  • Assign a dictionary value to a Variable in Python
  • Assign dictionary key-value pairs to variables in Python
  • Assign dictionary key-value pairs to variables using exec()

# Assign a dictionary value to a Variable in Python

Use bracket notation to assign a dictionary value to a variable, e.g. first = my_dict['first_name'] .

The left-hand side of the assignment is the variable's name and the right-hand side is the value.

assign dictionary value to variable

The first example uses square brackets to access a dictionary key and assigns the corresponding value to a variable.

If you need to access the dictionary value using an index , use the dict.values() method.

The dict.values method returns a new view of the dictionary's values.

We had to use the list() class to convert the view object to a list because view objects are not subscriptable (cannot be accessed at an index).

You can use the same approach if you have the key stored in a variable.

If you try to access a dictionary key that doesn't exist using square brackets, you'd get a KeyError .

On the other hand, the dict.get() method returns None for non-existent keys by default.

The dict.get method returns the value for the given key if the key is in the dictionary, otherwise a default value is returned.

The method takes the following 2 parameters:

If a value for the default parameter is not provided, it defaults to None , so the get() method never raises a KeyError .

If you need to assign the key-value pairs of a dictionary to variables, update the locals() dictionary.

# Assign dictionary key-value pairs to variables in Python

Update the locals() dictionary to assign the key-value pairs of a dictionary to variables.

assign dictionary key value pairs to variables

The first example uses the locals() dictionary to assign the key-value pairs of a dictionary to local variables.

The locals() function returns a dictionary that contains the current scope's local variables.

The dict.update method updates the dictionary with the key-value pairs from the provided value.

You can access the variables directly after calling the dict.update() method.

The SimpleNamespace class can be initialized with keyword arguments.

The keys of the dictionary are accessible as attributes on the namespace object.

Alternatively, you can use the exec() function.

# Assign dictionary key-value pairs to variables using exec()

This is a three-step process:

  • Iterate over the dictionary's items.
  • Use the exec() function to assign each key-value pair to a variable.
  • The exec() function supports dynamic execution of Python code.

assign dictionary key value pairs to variables using exec

The dict.items method returns a new view of the dictionary's items ((key, value) pairs).

On each iteration, we use the exec() function to assign the current key-value pair to a variable.

The exec function supports dynamic execution of Python code.

The function takes a string, parses it as a suite of Python statements and runs the code.

Which approach you pick is a matter of personal preference. I'd go with the SimpleNamespace class to avoid any linting errors for trying to access undefined variables.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

  • Check if all values in a Dictionary are equal in Python
  • How to Replace values in a Dictionary in Python
  • Get multiple values from a Dictionary in Python
  • Get random Key and Value from a Dictionary in Python
  • Join the Keys or Values of Dictionary into String in Python
  • Multiply the Values in a Dictionary in Python
  • Print specific key-value pairs of a dictionary in Python
  • How to set all Dictionary values to 0 in Python
  • Sum all values in a Dictionary or List of Dicts in Python
  • Swap the keys and values in a Dictionary in Python

book cover

Borislav Hadzhiev

Web Developer

buy me a coffee

Copyright © 2024 Borislav Hadzhiev

Python Tutorial

File handling, python modules, python numpy, python pandas, python matplotlib, python scipy, machine learning, python mysql, python mongodb, python reference, module reference, python how to, python examples, python lists.

Lists are used to store multiple items in a single variable.

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.

Lists are created using square brackets:

Create a List:

List items are ordered, changeable, and allow duplicate values.

List items are indexed, the first item has index [0] , the second item has index [1] etc.

When we say that lists are ordered, it means that the items have a defined order, and that order will not change.

If you add new items to a list, the new items will be placed at the end of the list.

Note: There are some list methods that will change the order, but in general: the order of the items will not change.

The list is changeable, meaning that we can change, add, and remove items in a list after it has been created.

Allow Duplicates

Since lists are indexed, lists can have items with the same value:

Lists allow duplicate values:

Advertisement

List Length

To determine how many items a list has, use the len() function:

Print the number of items in the list:

List Items - Data Types

List items can be of any data type:

String, int and boolean data types:

A list can contain different data types:

A list with strings, integers and boolean values:

From Python's perspective, lists are defined as objects with the data type 'list':

What is the data type of a list?

The list() Constructor

It is also possible to use the list() constructor when creating a new list.

Using the list() constructor to make a List:

Python Collections (Arrays)

There are four collection data types in the Python programming language:

  • List is a collection which is ordered and changeable. Allows duplicate members.
  • Tuple is a collection which is ordered and unchangeable. Allows duplicate members.
  • Set is a collection which is unordered, unchangeable*, and unindexed. No duplicate members.
  • Dictionary is a collection which is ordered** and changeable. No duplicate members.

*Set items are unchangeable, but you can remove and/or add items whenever you like.

**As of Python version 3.7, dictionaries are ordered . In Python 3.6 and earlier, dictionaries are unordered .

When choosing a collection type, it is useful to understand the properties of that type. Choosing the right type for a particular data set could mean retention of meaning, and, it could mean an increase in efficiency or security.

Get Certified

COLOR PICKER

colorpicker

Report Error

If you want to report an error, or if you want to make a suggestion, do not hesitate to send us an e-mail:

[email protected]

Top Tutorials

Top references, top examples, get certified.

How to search value by using key from list of dictionaries

list_of_dicts = [ {‘name’: ‘Alice’, ‘age’: 30}, {‘height’: 5, ‘weight’: 25}, {‘nickname’: ‘Charlie’} ]

from this mentioned list how to verify if particular key have particular value

You can use collections.ChainMap to create a consolidated mapping view to the underlying list of dicts:

Related Topics

  • Get Inspired
  • Announcements

Gemini 1.5: Our next-generation model, now available for Private Preview in Google AI Studio

February 15, 2024

python assign key to list

Last week, we released Gemini 1.0 Ultra in Gemini Advanced. You can try it out now by signing up for a Gemini Advanced subscription . The 1.0 Ultra model, accessible via the Gemini API, has seen a lot of interest and continues to roll out to select developers and partners in Google AI Studio .

Today, we’re also excited to introduce our next-generation Gemini 1.5 model , which uses a new Mixture-of-Experts (MoE) approach to improve efficiency. It routes your request to a group of smaller "expert” neural networks so responses are faster and higher quality.

Developers can sign up for our Private Preview of Gemini 1.5 Pro , our mid-sized multimodal model optimized for scaling across a wide-range of tasks. The model features a new, experimental 1 million token context window, and will be available to try out in  Google AI Studio . Google AI Studio is the fastest way to build with Gemini models and enables developers to easily integrate the Gemini API in their applications. It’s available in 38 languages across 180+ countries and territories .

1,000,000 tokens: Unlocking new use cases for developers

Before today, the largest context window in the world for a publicly available large language model was 200,000 tokens. We’ve been able to significantly increase this — running up to 1 million tokens consistently, achieving the longest context window of any large-scale foundation model. Gemini 1.5 Pro will come with a 128,000 token context window by default, but today’s Private Preview will have access to the experimental 1 million token context window.

We’re excited about the new possibilities that larger context windows enable. You can directly upload large PDFs, code repositories, or even lengthy videos as prompts in Google AI Studio. Gemini 1.5 Pro will then reason across modalities and output text.

Upload multiple files and ask questions We’ve added the ability for developers to upload multiple files, like PDFs, and ask questions in Google AI Studio. The larger context window allows the model to take in more information — making the output more consistent, relevant and useful. With this 1 million token context window, we’ve been able to load in over 700,000 words of text in one go. Gemini 1.5 Pro can find and reason from particular quotes across the Apollo 11 PDF transcript. 
[Video sped up for demo purposes]
Query an entire code repository The large context window also enables a deep analysis of an entire codebase, helping Gemini models grasp complex relationships, patterns, and understanding of code. A developer could upload a new codebase directly from their computer or via Google Drive, and use the model to onboard quickly and gain an understanding of the code. Gemini 1.5 Pro can help developers boost productivity when learning a new codebase.  
Add a full length video Gemini 1.5 Pro can also reason across up to 1 hour of video. When you attach a video, Google AI Studio breaks it down into thousands of frames (without audio), and then you can perform highly sophisticated reasoning and problem-solving tasks since the Gemini models are multimodal. Gemini 1.5 Pro can perform reasoning and problem-solving tasks across video and other visual inputs.  

More ways for developers to build with Gemini models

In addition to bringing you the latest model innovations, we’re also making it easier for you to build with Gemini:

Easy tuning. Provide a set of examples, and you can customize Gemini for your specific needs in minutes from inside Google AI Studio. This feature rolls out in the next few days. 
New developer surfaces . Integrate the Gemini API to build new AI-powered features today with new Firebase Extensions , across your development workspace in Project IDX , or with our newly released Google AI Dart SDK . 
Lower pricing for Gemini 1.0 Pro . We’re also updating the 1.0 Pro model, which offers a good balance of cost and performance for many AI tasks. Today’s stable version is priced 50% less for text inputs and 25% less for outputs than previously announced. The upcoming pay-as-you-go plans for AI Studio are coming soon.

Since December, developers of all sizes have been building with Gemini models, and we’re excited to turn cutting edge research into early developer products in Google AI Studio . Expect some latency in this preview version due to the experimental nature of the large context window feature, but we’re excited to start a phased rollout as we continue to fine-tune the model and get your feedback. We hope you enjoy experimenting with it early on, like we have.

5 Effective Ways to Convert Python Dictionary Keys to Index

💡 Problem Formulation: In Python, dictionaries do not maintain a fixed order until Python 3.7, and even then, indices are not directly associated with dictionary keys. The task is to convert dictionary keys to numerical indices, which can have various applications such as sorting, storage, and data manipulation. As an example, given a dictionary {'apple': 1, 'banana': 2, 'cherry': 3} , the desired output is a way to map each key to its corresponding index, e.g., ‘apple’ -> 0, ‘banana’ -> 1, ‘cherry’ -> 2.

Method 1: Enumerate and Dictionary Comprehension

This method involves using the enumerate() function and a dictionary comprehension to create a new dictionary that maps each key to its index. The index is obtained by enumerating through the original dictionary’s keys.

Here’s an example:

This code snippet creates a new dictionary where each key from the original_dict is associated with its corresponding index. This is a clean and readable solution that takes advantage of Python’s comprehensions and enumerate function.

Method 2: Using the Built-in dict.keys() Method and List Indexing

Create a list of dictionary keys using the dict.keys() method, then use list indexing to assign indices to each key. This approach is straightforward and works well with newer Python versions, where dictionaries maintain insertion order by default.

In the code, keys_list stores the dictionary keys in list form. The dictionary comprehension then iterates over the list, assigning each key its corresponding index within the list.

Method 3: Zip and Range Function

This technique utilizes the zip() function to combine a range object, which generates indices, with the keys from the dictionary. This is efficient and works in all Python versions, but order may not be preserved in versions before Python 3.7.

The code snippet creates a range object that serves as a source of indices, and the zip() function pairs each key with its corresponding index. This tuple pair is then converted into a dictionary.

Method 4: Iterating and Adding to a New Dictionary

Manually iterate through the dictionary keys and assign each key an incrementing index, storing the results in a new dictionary. This method offers fine control over index assignments and is clear in intent.

The code above iterates over the dictionary keys with an enumeration, manually inserting each key-index pair into key_index_map .

Bonus One-Liner Method 5: Using the items() Method

Leverage the items() method to iterate over key-value pairs and enumerate them directly inside a dictionary comprehension for a succinct one-liner solution.

This concise snippet uses a dictionary comprehension that iterates over enumerated key-value pairs of the original dictionary, assigning the index to the key.

Summary/Discussion

  • Method 1: Enumerate and Dictionary Comprehension. Strengths: Concise and uses Python best practices. Weaknesses: Order not guaranteed in Python versions before 3.7.
  • Method 2: dict.keys() Method and List Indexing. Strengths: Explicit and maintainable. Weaknesses: Can be slightly less efficient because of the list indexing operation.
  • Method 3: Zip and Range Function. Strengths: Efficient and concise. Weaknesses: Order could be an issue before Python 3.7.
  • Method 4: Iterative Approach. Strengths: Explicit and offers control over the process. Weaknesses: More verbose than other methods.
  • Method 5: items() Method One-Liner. Strengths: Extremely concise. Weaknesses: Might be less readable for beginners.

Emily Rosemary Collins is a tech enthusiast with a strong background in computer science, always staying up-to-date with the latest trends and innovations. Apart from her love for technology, Emily enjoys exploring the great outdoors, participating in local community events, and dedicating her free time to painting and photography. Her interests and passion for personal growth make her an engaging conversationalist and a reliable source of knowledge in the ever-evolving world of technology.

python assign key to list

Create a form in Word that users can complete or print

In Word, you can create a form that others can fill out and save or print.  To do this, you will start with baseline content in a document, potentially via a form template.  Then you can add content controls for elements such as check boxes, text boxes, date pickers, and drop-down lists. Optionally, these content controls can be linked to database information.  Following are the recommended action steps in sequence.  

Show the Developer tab

In Word, be sure you have the Developer tab displayed in the ribbon.  (See how here:  Show the developer tab .)

Open a template or a blank document on which to base the form

You can start with a template or just start from scratch with a blank document.

Start with a form template

Go to File > New .

In the  Search for online templates  field, type  Forms or the kind of form you want. Then press Enter .

In the displayed results, right-click any item, then select  Create. 

Start with a blank document 

Select Blank document .

Add content to the form

Go to the  Developer  tab Controls section where you can choose controls to add to your document or form. Hover over any icon therein to see what control type it represents. The various control types are described below. You can set properties on a control once it has been inserted.

To delete a content control, right-click it, then select Remove content control  in the pop-up menu. 

Note:  You can print a form that was created via content controls. However, the boxes around the content controls will not print.

Insert a text control

The rich text content control enables users to format text (e.g., bold, italic) and type multiple paragraphs. To limit these capabilities, use the plain text content control . 

Click or tap where you want to insert the control.

Rich text control button

To learn about setting specific properties on these controls, see Set or change properties for content controls .

Insert a picture control

A picture control is most often used for templates, but you can also add a picture control to a form.

Picture control button

Insert a building block control

Use a building block control  when you want users to choose a specific block of text. These are helpful when you need to add different boilerplate text depending on the document's specific purpose. You can create rich text content controls for each version of the boilerplate text, and then use a building block control as the container for the rich text content controls.

building block gallery control

Select Developer and content controls for the building block.

Developer tab showing content controls

Insert a combo box or a drop-down list

In a combo box, users can select from a list of choices that you provide or they can type in their own information. In a drop-down list, users can only select from the list of choices.

combo box button

Select the content control, and then select Properties .

To create a list of choices, select Add under Drop-Down List Properties .

Type a choice in Display Name , such as Yes , No , or Maybe .

Repeat this step until all of the choices are in the drop-down list.

Fill in any other properties that you want.

Note:  If you select the Contents cannot be edited check box, users won’t be able to click a choice.

Insert a date picker

Click or tap where you want to insert the date picker control.

Date picker button

Insert a check box

Click or tap where you want to insert the check box control.

Check box button

Use the legacy form controls

Legacy form controls are for compatibility with older versions of Word and consist of legacy form and Active X controls.

Click or tap where you want to insert a legacy control.

Legacy control button

Select the Legacy Form control or Active X Control that you want to include.

Set or change properties for content controls

Each content control has properties that you can set or change. For example, the Date Picker control offers options for the format you want to use to display the date.

Select the content control that you want to change.

Go to Developer > Properties .

Controls Properties  button

Change the properties that you want.

Add protection to a form

If you want to limit how much others can edit or format a form, use the Restrict Editing command:

Open the form that you want to lock or protect.

Select Developer > Restrict Editing .

Restrict editing button

After selecting restrictions, select Yes, Start Enforcing Protection .

Restrict editing panel

Advanced Tip:

If you want to protect only parts of the document, separate the document into sections and only protect the sections you want.

To do this, choose Select Sections in the Restrict Editing panel. For more info on sections, see Insert a section break .

Sections selector on Resrict sections panel

If the developer tab isn't displayed in the ribbon, see Show the Developer tab .

Open a template or use a blank document

To create a form in Word that others can fill out, start with a template or document and add content controls. Content controls include things like check boxes, text boxes, and drop-down lists. If you’re familiar with databases, these content controls can even be linked to data.

Go to File > New from Template .

New from template option

In Search, type form .

Double-click the template you want to use.

Select File > Save As , and pick a location to save the form.

In Save As , type a file name and then select Save .

Start with a blank document

Go to File > New Document .

New document option

Go to File > Save As .

Go to Developer , and then choose the controls that you want to add to the document or form. To remove a content control, select the control and press Delete. You can set Options on controls once inserted. From Options, you can add entry and exit macros to run when users interact with the controls, as well as list items for combo boxes, .

Adding content controls to your form

In the document, click or tap where you want to add a content control.

On Developer , select Text Box , Check Box , or Combo Box .

Developer tab with content controls

To set specific properties for the control, select Options , and set .

Repeat steps 1 through 3 for each control that you want to add.

Set options

Options let you set common settings, as well as control specific settings. Select a control and then select Options to set up or make changes.

Set common properties.

Select Macro to Run on lets you choose a recorded or custom macro to run on Entry or Exit from the field.

Bookmark Set a unique name or bookmark for each control.

Calculate on exit This forces Word to run or refresh any calculations, such as total price when the user exits the field.

Add Help Text Give hints or instructions for each field.

OK Saves settings and exits the panel.

Cancel Forgets changes and exits the panel.

Set specific properties for a Text box

Type Select form Regular text, Number, Date, Current Date, Current Time, or Calculation.

Default text sets optional instructional text that's displayed in the text box before the user types in the field. Set Text box enabled to allow the user to enter text into the field.

Maximum length sets the length of text that a user can enter. The default is Unlimited .

Text format can set whether text automatically formats to Uppercase , Lowercase , First capital, or Title case .

Text box enabled Lets the user enter text into a field. If there is default text, user text replaces it.

Set specific properties for a Check box .

Default Value Choose between Not checked or checked as default.

Checkbox size Set a size Exactly or Auto to change size as needed.

Check box enabled Lets the user check or clear the text box.

Set specific properties for a Combo box

Drop-down item Type in strings for the list box items. Press + or Enter to add an item to the list.

Items in drop-down list Shows your current list. Select an item and use the up or down arrows to change the order, Press - to remove a selected item.

Drop-down enabled Lets the user open the combo box and make selections.

Protect the form

Go to Developer > Protect Form .

Protect form button on the Developer tab

Note:  To unprotect the form and continue editing, select Protect Form again.

Save and close the form.

Test the form (optional)

If you want, you can test the form before you distribute it.

Protect the form.

Reopen the form, fill it out as the user would, and then save a copy.

Creating fillable forms isn’t available in Word for the web.

You can create the form with the desktop version of Word with the instructions in Create a fillable form .

When you save the document and reopen it in Word for the web, you’ll see the changes you made.

Facebook

Need more help?

Want more options.

Explore subscription benefits, browse training courses, learn how to secure your device, and more.

python assign key to list

Microsoft 365 subscription benefits

python assign key to list

Microsoft 365 training

python assign key to list

Microsoft security

python assign key to list

Accessibility center

Communities help you ask and answer questions, give feedback, and hear from experts with rich knowledge.

python assign key to list

Ask the Microsoft Community

python assign key to list

Microsoft Tech Community

python assign key to list

Windows Insiders

Microsoft 365 Insiders

Was this information helpful?

Thank you for your feedback.

IMAGES

  1. Izip python syntax with a list as input

    python assign key to list

  2. Python Dictionary Values To List

    python assign key to list

  3. Introduction To Python List Methods With Practical Questions

    python assign key to list

  4. How to Define and Use Python Lists

    python assign key to list

  5. Python Dictionary keys function

    python assign key to list

  6. Python List

    python assign key to list

VIDEO

  1. Python-Lists

  2. Lists

  3. PYTHON : LIST IN PYTHON

  4. Learn Python

  5. "Introduction to Python "List Part2 V07

  6. List in python

COMMENTS

  1. Python

    Method #1: Using list comprehension This is one of the ways in which this task can be performed. In this, we extract each element of dictionary value list to checklist value occurrence, if matched, we assign that key's value to that index. Python3 test_list = [4, 6, 3, 10, 5, 3] print("The original list : " + str(test_list))

  2. How to initialize a dict with keys from a list and empty value in Python?

    How to initialize a dict with keys from a list and empty value in Python? Ask Question Asked 14 years ago Modified 1 year, 1 month ago Viewed 484k times 370 I'd like to get from this: keys = [1,2,3] to this: {1: None, 2: None, 3: None} Is there a pythonic way of doing it? This is an ugly way to do it: >>> keys = [1,2,3] >>> dict([(1,2)]) {1: 2}

  3. 5 Best Ways to Convert Python Dictionary Keys to a List

    Method 3: Using the dict.keys () Method Directly. The keys () method can be used directly without converting the result into a list. The keys view object is iterable and can be used in for loops and other contexts where an iterable is required. However, it doesn't support indexing and has limited list operations.

  4. Convert Python Dictionary Keys to List

    1. Convert dictionary keys to a list using dict.keys () In the following program, we have a dictionary initialized with three key:value pairs. We will use dict.keys () method to get the dict_keys object. We pass dict.keys () as argument to list () constructor. list () returns the list of keys. Python Program

  5. Python's Assignment Operator: Write Robust Assignments

    Indices and slices of mutable sequences, like a_list[i] and a_list[i:j] Dictionary keys, like a_dict[key] This list isn't exhaustive. However, it gives you some idea of how flexible these statements are. You can even assign multiple values to an equal number of variables in a single line, commonly known as parallel assignment.

  6. How to use a List as a key of a Dictionary in Python 3?

    We can use integer, string, tuples as dictionary keys but cannot use list as a key of it . The reason is explained below . How does Python Dictionaries search their keys If the Python dictionaries just iterate over their keys to check if the given keys are present or not it would take O (N) time.

  7. Python: Add Key:Value Pair to Dictionary • datagy

    The easiest way to add an item to a Python dictionary is simply to assign a value to a new key. Python dictionaries don't have a method by which to append a new key:value pair. Because of this, direct assignment is the primary way of adding new items to a dictionary. Let's take a look at how we can add an item to a dictionary:

  8. Python List (With Examples)

    Access Elements Using Index We use index numbers to access list elements. For example, languages = ['Python', 'Swift', 'C++'] # access the first element print (languages [0]) # Python # access the third element print (languages [2]) # C++ Access List Elements More on Accessing List Elements Negative Indexing in Python

  9. 5 Best Ways to Make a Python List of Dicts Unique by Key

    Weaknesses: Might be overkill for simple cases. Method 4: Using itertools.groupby (). Strengths: Very powerful for more complex grouping. Weaknesses: Requires pre-sorting of the list which can be inefficient. Bonus Method 5: One-Liner with dict.fromkeys (). Strengths: Extremely compact.

  10. python

    How to assign list values to dictionary keys? Ask Question Asked 3 years, 4 months ago Modified 3 years ago Viewed 4k times 0 categories = {'player_name': None, 'player_id': None, 'season': None} L = ['Player 1', 'player_1', '2020'] How can I iterate over list and assign its values to the corresponding keys? so it would become something like:

  11. Effortlessly Add Keys to Python Dictionaries: A Complete Guide

    To add a new key-value pair with a tuple key, we can simply use the bracket notation to assign a value to a new tuple key ('b', 2) like so: my_dict[('b', 2)] = 'banana'. Add key to dictionary using list comprehension

  12. Python: How to Add Keys to a Dictionary

    In Python, we can add multiple key-value pairs to an existing dictionary. This is achieved by using the update () method. This method takes an argument of type dict or any iterable that has the length of two - like ( (key1, value1),), and updates the dictionary with new key-value pairs.

  13. Assign a dictionary Key or Value to variable in Python

    main.py my_dict = { 'first_name': 'Bobby', 'last_name': 'Hadz', 'site': 'bobbyhadz.com', } first = list(my_dict.values())[0] print(first) # 👉️ Bobby Python indexes are zero-based, so the first item in a list has an index of 0, and the last item has an index of -1 or len (my_list) - 1.

  14. Python Lists

    mylist = ["apple", "banana", "cherry"] List Lists are used to store multiple items in a single variable. 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. Lists are created using square brackets: Example Get your own Python Server

  15. How to use a list as a key in python dictionary

    1 Why would you use a mutable container as a key?? - user1971598 Aug 16, 2014 at 19:20 To build on the comment from Jon Clements, Python's syntax also plays nicely with tuples as dict keys. Consider this example dict: d = { (1,2) : 3, (10,20) : 30 }. To access a key, you can then write: d [1,2]. - FMc Aug 16, 2014 at 19:23

  16. How to Add Multiple Values to a Key in a Python Dictionary

    Method 1: Adding Multiple Values to a Dictionary using Operators. We can use the assignment operator += to add values to a specific key in the same way we use it to add values to variables. word1 = 'sleeping '. word1 += 'parrot'.

  17. How to search value by using key from list of dictionaries

    list_of_dicts = [{'name': 'Alice', 'age': 30}, {'height': 5, 'weight': 25}, {'nickname': 'Charlie'}] from this mentioned list how to ...

  18. how to assign list of values to a key using OrderedDict in python

    2,912 16 53 70 As a side note, you almost never want to maintain an explicit loop counter like that. Just for i, key in enumerate (keys): instead. (Actually, in this case, you don't even need the loop counter in the first place. Just for key, val1, val2 in zip (keys, vals1, vals2): instead.) - abarnert Nov 7, 2012 at 8:15

  19. Gemini 1.5: Our next-generation model, now available for Private

    Posted by Jaclyn Konzelmann and Wiktor Gworek - Google Labs. Last week, we released Gemini 1.0 Ultra in Gemini Advanced. You can try it out now by signing up for a Gemini Advanced subscription.The 1.0 Ultra model, accessible via the Gemini API, has seen a lot of interest and continues to roll out to select developers and partners in Google AI Studio.

  20. 5 Effective Ways to Convert Python Dictionary Keys to Index

    Method 2: Using the Built-in dict.keys () Method and List Indexing. Create a list of dictionary keys using the dict.keys () method, then use list indexing to assign indices to each key. This approach is straightforward and works well with newer Python versions, where dictionaries maintain insertion order by default.

  21. python

    0. One way of doing it: dict={} for item in list: if item not in dict.keys(): dict[item] = None. dict[item]=value. If item is not present in dictionary's keys, just create one with None as starting value. Then, assign value to key (now You're sure it is there).

  22. Create a form in Word that users can complete or print

    Add content to the form. Go to the Developer tab Controls section where you can choose controls to add to your document or form. Hover over any icon therein to see what control type it represents. The various control types are described below. You can set properties on a control once it has been inserted.