Python Dictionary

Python Dictionary is the collection of multiple data like the list and tuple. The main difference between the list and the dictionary is that the dictionary elements are unordered. Whereas, dictionary elements always have a key:value pair.

Example to create and declare python dictionary

my_dictionary =	{
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
print(my_dictionary )

Creating dictionary using the dict keyword

We can also create the dictionary by using a dict keyword.

Example of creating a dictionary using the dict keyword

my_dictionary =dict(
  Title = "TutorialsClass",
  URL = "https://tutorialsclass.com/",
  Year = 2019
)

print(my_dictionary)

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Printing a dictionary

Printing a dictionary is simple like printing a variable.

Example to print dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
print(my_dictionary)

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Topics to remember about Python Dictionary

Dictionary in Python are ordered and have a definite count. Also, we can concatenate the sets.

Printing a specific element from the Dictionary

We can print the specific value from the dictionary by specifying a key.

Example to print a specific element of dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
print(my_dictionary["Year"])

Example to print a specific element of dictionary using the get() function

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
print(my_dictionary.get("Year"))

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Python Dictionary – Modyfing or updating elements:

We can modify elements from the dictionary directly.

Example to update the elements of dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary ["Year"] = 2018
print(my_dictionary )

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Adding elements to a dictionary

We can add any number of elements in a dictionary directly without using some inbuilt functions.

Example to add new element to dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary ["Birth"] = 2018
print(my_dictionary )

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Copying one dictionary to the other dictionary

We can easily copy one dictionary to the other by using the copy() method.

Example to copy one dictionary to other dictionary

my_dictionary_1 = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary_2 = my_dictionary_1.copy()
print(my_dictionary_2)

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Checking length of a Python dictionary

With the help of the len() function we can check how many numbers of key:value pair exist in the dictionary. 

Example to calculate the length of dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
print(len(my_dictionary ))

Description of Output

Here you can see the output is 3, which means there are three key:value pairs in our this Dictionary.

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Python Dictionary- Removing the specific element from the dictionary

We can remove the value in many ways.

Example removing a specific element from the user With the help of pop() function

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary .pop("Year")
print(my_dictionary )

Example to remove a specific element from the user With the help del keyword

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
del my_dictionary["Year"]
print(my_dictionary )

Example to remove a specific element from the user With the help popitem() function

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary .popitem( )
print(my_dictionary )

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Removing all elements from the dictionary

We can remove all the key:value pairs with the help of clear() function, we can remove all the elements from the dictionary.

Example to remove all the elements from dictionary

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
my_dictionary .clear()
print(my_dictionary )

Description of Output

Here you can see that all the items from the dictionary have been cleared.

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Python Dictionary – Delete the dictionary

In Python programming, we can delete the whole dictionary as well using the del keyword

my_dictionary ={
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
del my_dictionary 

Description of Output

Here you can see that the output is blank because we have deleted the dictionary. So, it will not return anything.

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Checking if any item exists in Python Dictionary

Like a list, we can easily check if an element is present in the dictionary or not.

Example to an element is exists in python dictionary or not

my_dictionary = {
  "Title": "TutorialsClass",
  "URL": "https://tutorialsclass.com/",
  "Year": 2019
}
if "Year" in my_dictionary :
  print("Yes, 'Year' is in this dictionary")
else:
   print("No, 'Year' is not in this dictionary")

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Important Points about Python Dictionary

• Keys in Dictionary can’t be duplicated.
• We can also use for loop for printing the dictionary.

Example to print the keys and value by using for loop

my_dictionary = {
    "Title": "TutorialsClass",
    "URL": "https://tutorialsclass.com/",
    "Year": 2019
}
# Printing all key names in the dictionary one by one
for x in my_dictionary:
    print(x)

 # Printing all the values in the dictionary one by one
for x in my_dictionary:
    print(my_dictionary[x])

# Another way to print all the values in the dictionary one by one

for x in my_dictionary.values():
    print(x)


# printing both the values and keys
for x, y in my_dictionary.items():
    print(x, y)

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