Python Dictionary

A dictionary consists of a collection of key-value pairs. It does not allow duplicates. Key is the important part of the dictionary for data manipulation. This section will cover all about Python dictionary.


Objectives

  • Python Dictionary Syntax

  • Create and assign value in Dictionary

  • Python Dictionary Access elements

  • Dictionary data manipulations

  • Python List of Dictionary methods and it’s task


Python Dictionary Syntax

dictionary = {"key" : "value"}
Here

  • Keys are unique within a dictionary while values may not be.

  • The keys must be of an immutable data type such as strings, numbers, or tuples

  • The values of a dictionary can be of any type.


Create and assign value in Python Dictionary

# Define a dictionary
string_dictionary = {}

# Assign value to a dictionary
string_dictionary = {
    "name": "Touhid Mia",
    "country": "Bangladesh",
    "age": 28,
}


Python Dictionary Access elements

This part you are going to learn access dictionary elements using various way, let’s jump into the codes.

Common Dictionary

# Declare Dictionary for access data element
dictionary_data = {
    "name": "Touhid Mia",
    "country": "Bangladesh",
    "age": 28,
    "height": 5.10,
    "isBeard": True,
}


Access element by key

Code

# Access element by key
name = dictionary_data["name"]
print(name)

Output

Touhid Mia

Process finished with exit code 0


Access element by get function

Code

# Access element by get function
name = dictionary_data.get("name")
print(name)

Output

Touhid Mia

Process finished with exit code 0


Access dictionary all keys

Code

# Access dictionary all keys
all_keys = dictionary_data.keys()
print(all_keys)

Output

dict_keys(['name', 'country', 'age', 'height', 'isBeard'])

Process finished with exit code 0


Access dictionary all values

Code

# Access dictionary all values
all_keys = dictionary_data.values()
print(all_keys)

Output

dict_values(['Touhid Mia', 'Bangladesh', 28, 5.1, True])

Process finished with exit code 0


Access dictionary items as tuples of list

Code

# Access dictionary items as tuples of list
list_of_tuples = dictionary_data.items()
print(list_of_tuples)

Output

dict_items([('name', 'Touhid Mia'), ('country', 'Bangladesh'), ('age', 28), ('height', 5.1), ('isBeard', True)])

Process finished with exit code 0


Check dictionary key is exist on it

Code

# Check dictionary key is exist on it
if "name" in dictionary_data:
    print("Yes key exist")
else:
    print("Key not exist")

Output

Yes key exist

Process finished with exit code 0


Print each element of dictionary by loop

Code

# Print each element of dictionary by loop
for key in dictionary_data:
    value = dictionary_data[key]  # Access value using key
    print("Key : " + key + ", Value : " + str(value))

Output

Key : name, Value : Touhid Mia
Key : country, Value : Bangladesh
Key : age, Value : 28
Key : height, Value : 5.1
Key : isBeard, Value : True

Process finished with exit code 0


Python Dictionary data manipulations

Earlier part you saw that how to retrieve or access element from a dictionary, this part you learn how to add, remove, update data to dictionary

Common Dictionary

# Declare Dictionary for access data element
dictionary_data = {
    "name": "Touhid Mia",
    "country": "Bangladesh",
    "age": 28,
    "height": 5.10,
    "isBeard": True,
}


Dictionary add item using key

Code

# Dictionary add item using key
dictionary_data["isMarried"] = True
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'country': 'Bangladesh', 'age': 28, 'height': 5.1, 'isBeard': True, 'isMarried': True}

Process finished with exit code 0


Dictionary add item using update function

Code

# Dictionary add item using update function
dictionary_data.update({"hasChild": True})
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'country': 'Bangladesh', 'age': 28, 'height': 5.1, 'isBeard': True, 'isMarried': False, 'hasChild': True}

Process finished with exit code 0


Dictionary update item using key

Code

# Dictionary update item using key
dictionary_data["age"] = 30
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'country': 'Canada', 'age': 30, 'height': 5.1, 'isBeard': True, 'isMarried': True, 'hasChild': True}

Process finished with exit code 0


Dictionary update item using update function

Code

# Dictionary update item using update function
dictionary_data.update({"country": "Canada"})
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'country': 'Canada', 'age': 30, 'height': 5.1, 'isBeard': True, 'isMarried': True, 'hasChild': True}

Process finished with exit code 0


Dictionary remove item using key and pop function

Code

# Dictionary remove item using key and pop function
dictionary_data.pop("age")
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'country': 'Canada', 'height': 5.1, 'isBeard': True, 'isMarried': True, 'hasChild': True}

Process finished with exit code 0


Dictionary remove item using key and del

Code

# Dictionary remove item using key and del
del dictionary_data["country"]
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'height': 5.1, 'isBeard': True, 'isMarried': True, 'hasChild': True}

Process finished with exit code 0


Dictionary remove last inserted item by popitem function

Code

# Dictionary remove last inserted item by popitem function
dictionary_data.popitem()
print(dictionary_data)

Output

{'name': 'Touhid Mia', 'height': 5.1, 'isBeard': True, 'isMarried': True}

Process finished with exit code 0


Dictionary remove all item using clear function

Code

# Dictionary remove all item using clear function
dictionary_data.clear()
print(dictionary_data)

Output

{}

Process finished with exit code 0


Python List of Dictionary methods and it’s task

  • keys() : Returns a list containing the dictionary’s keys

  • values() : Returns a list of all the values in the dictionary

  • get() : Returns the value of the specified key

  • items() : Returns a list containing a tuple for each key value pair

  • clear() : Removes all the elements from the dictionary

  • copy() : Returns a copy of the dictionary

  • fromkeys() : Returns a dictionary with the specified keys and value

  • pop() : Removes the element with the specified key

  • popitem() : Removes the last inserted key-value pair

  • setdefault() : Returns the value of the specified key. If the key does not exist: insert the key, with the specified value

  • update() : Updates the dictionary with the specified key-value pairs


Python Dictionary video tutorial

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