How do i convert a dictionary to a list in python?

Python has different types of data structures to manage your data efficiently. Lists are simple sequential data, whereas a dictionary is a key-value pair data. Both of them have unique usability and is already been implemented with various helpful methods. Many times, we need to convert the dictionary to a list in Python or vice versa. In this post, we’ll look at all possible methods to do so.

Dictionary to List Conversion can be done in multiple ways. The most efficient way to do it is, calling the helping methods of the dictionary. Some methods like, items(), values(), and keys() are useful in extracting the data from dictionary. Moreover, you can also loop through the dictionary to find individual elements.

• What is a Dictionary in Python?
• What is a List in Python?
• Converting Dictionary to List in Python
  • 1. Dictionary to List Using .items() Method
  • 2. Using .keys() Method
  • 3. Using .values() Method
  • 4. Dictionary to List using loop + items() Method
  • 5. List Comprehension Method
  • 6. Using Zip Function
  • 7. Dictionary to List Using Iteration Method
  • 8. Dictionary to List using Collection Method
  • 9. Using Map Function
• Difference between Lists and Dictionary
• Dictionary to List – FAQs
• See Also
• Conclusion

What is a Dictionary in Python?

Dictionary is a data structure that stores the data as key-value formats. The order of elements is not reserved in the dictionary. When converting the dictionary data to the list, your order may change. Moreover, duplicates are not allowed in the dictionary.

Example –

d = {"name":"python", "version":3.9}

What is a List in Python?

List is a data structure that saves the values sequentially. Lists are termed as arrays in many other programming languages. In Python, lists have flexible lengths, and the elements inside them can be added or removed anytime. Unlike dictionaries, you can have duplicates in the list.

Example –

d = ["name", "python", "version", 3.9]

Converting Dictionary to List in Python

There are several ways of converting a dictionary to a list. We’ve tried our best to ensure that we cover the maximum methods possible. If you have any other method, please let us know in the comments.

1. Dictionary to List Using .items() Method

.items() method of the dictionary is used to iterate through all the key-value pairs of the dictionary. By default, they are stored as a tuple (key, value) in the iterator. Using list() will get you all the items converted to a list.

Code:

d = {"name":"python", "version":3.9}
new_list = list(d.items())
print(new_list)

Output:

[('name', 'python'), ('version', 3.9)]

2. Using .keys() Method

.keys() method gets you all the keys from the dictionary. Combining it with the list() function, you’ll get a list of all keys from the dictionary.

Tip: If you use .keys() and .values() method of the dictionary, make sure you don’t alter the dictionary in between. Otherwise, the sequence from key and value would mismatch.

Code:

d = {"name":"python", "version":3.9}
new_list = list(d.keys())
print(new_list)

Output:

['name', 'version']

3. Using .values() Method

.values() method from dictionaries can be used to get a list of values. Using list() function, we can convert values to a list.

Code:

d = {"name":"python", "version":3.9}
new_list = list(d.values())
print(new_list)

Output:

['python', 3.9]

4. Dictionary to List using loop + items() Method

Append is a method in python lists that allows you to add an element to the end of the list. By initializing empty elements and then looping through the dictionary.items(), we can append a new list [key, value] in the original list.

Code:

d = {"name":"python", "version":3.9}

new_list = [] 
for key, val in d.items(): 
    new_list.append([key, val]) 

print(new_list)

Output:

[['name', 'python'], ['version', 3.9]]

5. List Comprehension Method

List Comprehension is easy of initializing a list in python. Moreover, you can choose the value of elements in the same single line. Using dictionary.items() to fetch the key and values of the items, and then adding them to the list.

Code:

d = {"name":"python", "version":3.9}

new_list = [(k, v) for k, v in d.items()] 

print(new_list)

Output:

[('name', 'python'), ('version', 3.9)]

6. Using Zip Function

The zip function is a useful way of combining two lists/iterators. This way we can combine .keys() and .values() methods of the dictionary to get both the values simultaneously.

Code:

d = {"name":"python", "version":3.9}

new_list = zip(d.keys(), d.values()) 
new_list = list(new_list)

print(new_list)

Output:

[('name', 'python'), ('version', 3.9)]

7. Dictionary to List Using Iteration Method

Iteration is always your friend if you’re unaware of any methods of dictionaries. You can fetch the key by looping through the dictionary and once you have the key, you can use dictionary[key] to fetch its value. Following code uses a similar technique along with .append() function to push elements into a list.

Code:

d = {"name":"python", "version":3.9}

new_list = []

for i in d:
  k = [i, d[i]]
  new_list.append(k)

print(new_list)

Output:

[['name', 'python'], ['version', 3.9]]

8. Dictionary to List using Collection Method

You can create a named tuple in python by using collections.namedtuple(). This way you can declare a custom data structure along with a list of its members. In this case, we’ve used “name” and “value” to be its member.

Code:

import collections

d = {"name":"python", "version":3.9}

list_of_tuple = collections.namedtuple('List', 'name value') 
new_list = list(list_of_tuple(*item) for item in d.items()) 

print(new_list)

Output:

[List(name='name', value='python'), List(name='version', value=3.9)]

9. Using Map Function

map() is an inbuilt function that maps any function over an iterator/list. You can map the list() function over all the elements of d.items() to convert them into lists of lists. The following example will help you understand –

Code:

d = {"name":"python", "version":3.9}

new_list = list(map(list, d.items()))
print(new_list)

Output:

[['name', 'python'], ['version', 3.9]]

Difference between Lists and Dictionary

How do you get a value from a dictionary in a list Python?

In the dictionary, to get a value you have to provide its key. dictionary[key] is the correct syntax of getting a value from the dictionary for any key ‘key_item’. If you provide an incorrect key, it’ll throw KeyError.

How do you create an empty dictionary?

dictionary = {} is the syntax to create an empty dictionary. Use two curly brackets to initialize an empty dictionary.

How to Map Dictionary Value to List?

Map dictionary.get() over the list to get a list of values. map(dic.get, lst) is the correct syntax to do it.

How to add Dictionary to List in Python

Use the append() method of the list to add a dictionary to the list. Append ensure that you add a dictionary at the end of the list every time. Example –
x = []
x.append({“v”: 5})

See Also

Conclusion

Lists and dictionary are inter-changeable in python which comes very handy to the coders. Above are some of the ways that might help you in times of difficulty. Hope it helped.

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