Python – Convert List to Dictionary

Python List to Dictionary

There are many ways in which you can interpret the data in list as keys and values, and convert this list into a dictionary.

Some of the formats of lists are

• [key_1, value_1, key_2, value_2, ...] – Key:Value pairs as continuous elements of list.
• [key_1, key_2, ...], [value_1, value_2, ...] – Keys are in one list, and Values are in another list.
• [(key_1, value_1), (key_2, value_2), ...] Key:Value pairs as tuples, and these tuples are elements of the list.

Also, some of the other scenarios are:

• Converting Python List to dictionary with list element as key and index as value.
• Converting Python List to dictionary with list element as key and a default for value.

In this tutorial, we will learn how to convert these formats of list to dictionary, with the help of well detailed example programs.

Examples

1. Convert given list to a dictionary

In this example, we will convert the list of format [key_1, value_1, key_2, value_2, ...] to dictionary of {key_1:value_1, key_2:value_2, ...}.

We will use dictionary comprehension to convert this type of list to dictionary.

myList = ['a', 'apple', 'b', 'banana', 'c', 'cherry'] 
myDict = {myList[i]: myList[i + 1] for i in range(0, len(myList), 2)} 
print(myDict)

Output

{'a': 'apple', 'b': 'banana', 'c': 'cherry'}

2. Convert a list of keys and a list of values into a dictionary

In this example, we will convert a list of format [(key_1, value_1), (key_2, value_2), ...] to dictionary of {key_1:value_1, key_2:value_2, ...}.

We will use dictionary comprehension to convert this lists of keys and values to dictionary.

listKeys = ['a', 'b', 'c'] 
listValues = ['apple', 'banana', 'cherry']

myDict = {listKeys[i]: listValues[i] for i in range(0, len(listKeys), 1)} 
print(myDict)

Output

{'a': 'apple', 'b': 'banana', 'c': 'cherry'}

3. Convert list of tuples into a dictionary

In this example, we will convert a list of format [(key_1, value_1), (key_2, value_2), ...] to dictionary of {key_1:value_1, key_2:value_2, ...}.

We will use dictionary comprehension to convert list of tuples to dictionary.

myList = [('a', 'apple'), ('b', 'banana'), ('c', 'cherry')] 
myDict = {myList[i][0]: myList[i][1] for i in range(0, len(myList), 1)} 
print(myDict)

Output

{'a': 'apple', 'b': 'banana', 'c': 'cherry'}

4. Convert list into dictionary with index as value

In this example, we will convert a list of format [key_1, key_2, ...] to dictionary of {key_1:0, key_2:1, ...}.

myList = ['a', 'b', 'c'] 
myDict = {myList[i]: i for i in range(0, len(myList), 1)} 
print(myDict)

Output

{'a': 0, 'b': 1, 'c': 2}

5. Convert list of keys into a dictionary with a default value

In this example, we will convert a list of format [key_1, key_2, ...] to dictionary of {key_1:default_value, key_2:default_value, ...}.

myList = ['a', 'b', 'c'] 
defaultValue = 54
myDict = {myList[i]: defaultValue for i in range(0, len(myList), 1)} 
print(myDict)

Output

{'a': 54, 'b': 54, 'c': 54}

Summary

In this tutorial of Python Examples, we learned how to convert a Python List to Dictionary.