Python - Create a dictionary using list with none values

PythonServer Side ProgrammingProgramming

Suppose you are given a list but we want to convert it to dictionary. Dictionary elements hold two values are called key value pair, we will use in case of value. The elements of the list become keys and non will remain a placeholder.

With dict

The dict() constructor creates a dictionary in Python. So we will use it to create a dictionary. The fromkeys method is used to create the dictionary elements.

Example

 Live Demo

listA = ["Mon","Tue","Wed","Thu","Fri"]
print("Given list: \n", listA)

res = dict.fromkeys(listA)

# New List
print("The list of lists:\n",res)

Output

Running the above code gives us the following result −

Given list:
['Mon', 'Tue', 'Wed', 'Thu', 'Fri']
The list of lists:
{'Mon': None, 'Tue': None, 'Wed': None, 'Thu': None, 'Fri': None}

With zip and dict

We can also use the dict constructor with zip method so that each element is converted into a key value pair.

Example

 Live Demo

listA = ["Mon","Tue","Wed","Thu","Fri"]
print("Given list: \n", listA)

res = dict(zip(listA, [None]*len(listA)))

# New List
print("The list of lists:\n",res)

Output

Running the above code gives us the following result −

Given list:
   ['Mon', 'Tue', 'Wed', 'Thu', 'Fri']
The list of lists:
   {'Mon': None, 'Tue': None, 'Wed': None, 'Thu': None, 'Fri': None}

With dict comprehension

Create a for loop to loop through each element of the list and assign None as key.

Example

 Live Demo

listA = ["Mon","Tue","Wed","Thu","Fri"]
print("Given list: \n", listA)

res = {key: None for key in listA}

# New List
print("The list of lists:\n",res)

Output

Running the above code gives us the following result −

Given list:
   ['Mon', 'Tue', 'Wed', 'Thu', 'Fri']
The list of lists:
   {'Mon': None, 'Tue': None, 'Wed': None, 'Thu': None, 'Fri': None}
raja
Published on 22-Jul-2020 08:21:17
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