How to get a value for a given key from a Python dictionary?


In this article, we will show you how to get a value for the given key from a dictionary in Python. Below are the 4 different methods to accomplish this task −

  • Using dictionary indexing

  • Using dict.get() method

  • Using keys() Function

  • Using items() Function

Assume we have taken a dictionary containing key-value pairs. We will return the value for a given key from a given input dictionary.

Method 1: Using dictionary indexing

In Python, we can retrieve the value from a dictionary by using dict[key].

Algorithm (Steps)

Following are the Algorithm/steps to be followed to perform the desired task −

  • Create a variable to store the input dictionary

  • Get the value of a given key from the input dictionary by passing the key value to the input dictionary in [] brackets.

  • print the resultant value for a given key.

Example 1

The following program returns the index of the value for a given key from an input dictionary using the dict[key] method −

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # Printing the value of key 10 from a dictionary print("The value of key 10 from dictionary is =", demoDictionary[10])

Output

The value of key 10 from dictionary is = TutorialsPoint

If the key does not exist in a given input dictionary, a KeyError is raised.

Example 2

In the below code, the key 'hello' is not present in the input list. So, when we try to print the value of the key 'hello', a KeyError is returned. −

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # Printing the value of key 'hello' from a dictionary # A KeyError is raised as the hello key is NOT present in the dictionary print("The value of key 'hello' from a dictionary:", demoDictionary['hello'])

Output

Traceback (most recent call last):
  File "main.py", line 6, in 
    print("The value of key 'hello' from a dictionary:", demoDictionary['hello'])
KeyError: 'hello'

Handling the KeyError

The following code handles the KeyError returned in the above code using the try-except blocks −

Example

Here the except block statements will get executed if any error occurs. −

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # Handling KeyError using try-except blocks try: print(demoDictionary['hello']) except KeyError: print("No, The key for Value 'Hello' does not exist in the dictionary. Please check")

Output

No, The key for Value 'Hello' does not exist in the dictionary. Please check

Method 2: Using dict.get() method

We can get the value of a specified key from a dictionary by using the get() method of the dictionary without throwing an error, if the key does not exist.

As the first argument, specify the key. If the key exists, the corresponding value is returned; otherwise, None is returned.

Example 1

The following program returns the index of the value for a given key from an input dictionary using dict.get() method −

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # Printing the value of key 10 from a dictionary using get() method print("The value of key 10 from a dictionary:", demoDictionary.get(10)) # Printing the value of key 'hello' from a dictionary # As the hello key does not exist in the dictionary, it returns None print("The value of key 'hello' from a dictionary:", demoDictionary.get('hello'))

Output

The value of key 10 from a dictionary: TutorialsPoint
The value of key 'hello' from a dictionary: None

In the second argument, you can define the default value to be returned if the key does not exist.

Example 2

The following program returns the user-given message which is passed as a second argument if the key does not exist in the dictionary using dict.get() method −

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # Printing the value of key 'hello' from a dictionary # As the hello key does not exist in the dictionary, it returns the user-given message print("The value of key 'hello' from a dictionary:", demoDictionary.get('hello', "The Key does not exist"))

Output

The value of key 'hello' from a dictionary: The Key does not exist

Method 3: Using keys() Function

The following program returns the index of the value for a given key from an input dictionary using the keys() method

Following are the Algorithm/steps to be followed to perform the desired task −

  • Traverse in the dictionary keys using the keys() function(the dict. keys() method provides a view object that displays a list of all the keys in the dictionary in order of insertion).

  • Check if the given key is equal to the iterator value and if it is equal then print its corresponding value

Example

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} # enter the key for which the value to be obtained givenkey= 10 # Traversing the keys of the dictionary for i in demoDictionary.keys(): # checking whether the value of the iterator is equal to the above-entered key if(i==givenkey): # printing the value of the key print(demoDictionary[i])

Output

TutorialsPoint

Method 4: Using items() Function

Example

The following program returns the index of the value for a given key from an input dictionary using the items() method

# input dictionary demoDictionary = {10: 'TutorialsPoint', 12: 'Python', 14: 'Codes'} givenkey= 12 # Traversing in the key-value pairs of the dictionary using the items() function for key,val in demoDictionary.items(): # checking whether the key value of the iterator is equal to the above-entered key if(key==givenkey): print(val)

Output

Python

Conclusion

We learned how to get the value of the dictionary key using four different methods in this article. We also learned how to deal with errors when a key does not exist in the dictionary.

Updated on: 31-Oct-2023

28K+ Views

Kickstart Your Career

Get certified by completing the course

Get Started
Advertisements