Python dictionary is a group sort that shops information in key-value pairs. It’s unordered, changeable, and doesn’t permit duplicates. Dictionaries are very environment friendly for trying up and inserting information, as they use a method referred to as hashing to map keys to their related values. They’re a strong information construction that permits you to retailer and manipulate information in a key-value pair format. One widespread process when working with dictionaries is to append new values to an current dictionary. Whereas Python dictionaries shouldn’t have an append() methodology like lists do, a number of methods exist so as to add new key-value pairs to a dictionary. On this weblog submit, we are going to discover a few of these strategies and focus on when to make use of every one. So, let’s dive in!

Dictionary in Python

A dictionary is a crucial information sort in Python programming. It’s a assortment of knowledge values which are unordered. Python dictionary is used to retailer gadgets by which every merchandise has a key-value pair. The dictionary is made up of those key-value pairs, and this makes the dictionary extra optimized. 

For instance –

Dict = {1: 'Studying', 2: 'For', 3: 'Life'}
print(Dict)

Right here, 

The colon is used to pair keys with the values.

The comma is used as a separator for the weather. 

The output is:

{1: ‘Learnings’, 2: ‘For’, 3: ‘Life’}

Python dictionary append is solely used so as to add key/worth to the prevailing dictionary. The dictionary objects are mutable. Not like different objects, the dictionary merely shops a key together with its worth. Subsequently, the mix of a key and its subsequent worth represents a single component within the Python dictionary.  

Restrictions on Key Dictionaries

Beneath are enlisted some restrictions on the important thing dictionaries –

• A given key seems solely as soon as in a dictionary. Duplicates of keys are usually not allowed. 
• It received’t make sense when you map a specific key greater than as soon as. That is so as a result of the dictionary will map every key to its worth.
• In case of a duplication of a key, the final one will probably be thought-about.
• If a key’s specified a second time after the creation of a dictionary, then the second time will probably be thought-about as it would override the primary time.
• The important thing should be immutable, that means the information sort may be an integer, string, tuple, boolean, and many others. Subsequently, lists or one other dictionary can’t be used as they’re changeable.  

Find out how to append a component to a key in a dictionary with Python?

Making a Dictionary

In Python, you may create a dictionary simply utilizing mounted keys and values. The sequence of parts is positioned inside curly brackets, and key: values are separated by commas. It should be famous that the worth of keys may be repeated however can’t have duplicates. Additionally, keys ought to have immutable information varieties similar to strings, tuples, or numbers. 

Right here’s an instance –

# Making a Dictionary
# with Integer Keys
Dict = {1: 'Studying', 2: 'For', 3: Life}
print("nDictionary with the usage of Integer Keys: ")
print(Dict)
  
# Making a Dictionary
# with Combined keys
Dict = {'Identify': ‘Nice Studying’, 1: [1, 2, 3, 4]}
print("nDictionary with the usage of Combined Keys: ")
print(Dict)

The output is :

Dictionary with the usage of Integer Keys: 

{1: ‘Studying’, 2: ‘For’, 3: ‘Life’}

Dictionary with the usage of Combined Keys: 

{‘Identify’: ‘GreatLearning’, 1: [1, 2, 3, 4]}

Dictionary with integer keys

Right here’s how you can create a dictionary utilizing the integer keys –

# creating the dictionary
dict_a = {1 : "India", 2 : "UK", 3 : "US", 4 : "Canada"}

# printing the dictionary
print("Dictionary 'dict_a' is...")
print(dict_a)

# printing the keys solely
print("Dictionary 'dict_a' keys...")
for x in dict_a:
    print(x)

# printing the values solely
print("Dictionary 'dict_a' values...")
for x in dict_a.values():
    print(x)

# printing the keys & values
print("Dictionary 'dict_a' keys & values...")
for x, y in dict_a.gadgets():
    print(x, ':', y)

The output is:

Dictionary ‘dict_a’ is…

{1: ‘India’, 2: ‘USA’, 3: ‘UK’, 4: ‘Canada’}

Dictionary ‘dict_a’ keys…

1

2

3

4

Dictionary ‘dict_a’ values…

India

USA

UK

Canada

Dictionary ‘dict_a’ keys & values…

1 : India

2 : UK

3 : US

4 : Canada

Accessing parts of a dictionary

Key names are used to entry parts of a dictionary. To entry the weather, you should use sq. brackets ([‘key’]) with the important thing inside it. 

Right here’s an instance –

# Python program to exhibit
# accessing a component from a dictionary
  
# Making a Dictionary
Dict = {1: 'Studying', 'title': 'For', 3: 'Life'}
  
# accessing a component utilizing key
print("Accessing a component utilizing key:")
print(Dict['name'])
  
# accessing a component utilizing key
print("Accessing a component utilizing key:")
print(Dict[1])

The output is:

Accessing a component utilizing key:

For

Accessing a component utilizing key:

Life

Different methodology 

There’s one other methodology referred to as get() that’s used to entry parts from a dictionary. On this methodology, the secret’s accepted as an argument and returned with a worth. 

Right here’s an instance –

# Making a Dictionary
Dict = {1: 'Studying', 'title': 'For', 3: 'Life'}
  
# accessing a component utilizing get()
# methodology
print("Accessing a component utilizing get:")
print(Dict.get(3))

The output is:

Accessing a component utilizing get:

Life

Deleting component(s) in a dictionary

You possibly can delete parts in a dictionary utilizing the ‘del’ key phrase.

The syntax is –

del dict['yourkey']  #This may take away the component along with your key.

Use the next syntax to delete your complete dictionary –

del my_dict  # it will delete the dictionary with title my_dict

One other different is to make use of the clear() methodology. This methodology helps to wash the content material contained in the dictionary and empty it. The syntax is –

Allow us to test an instance of the deletion of parts that lead to emptying your complete dictionary –

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}
del my_dict['username']  # it would take away "username": "ABC" from my_dict
print(my_dict)
my_dict.clear()  # until will make the dictionarymy_dictempty
print(my_dict)
delmy_dict # it will delete the dictionarymy_dict
print(my_dict)

The output is:

{’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

{}

Traceback (most up-to-date name final):

  File “foremost.py”, line 7, in <module>

    print(my_dict)

NameError: title ‘my_dict’ will not be outlined

Deleting Component(s) from dictionary utilizing pop() methodology

The dict.pop() methodology can be used to delete parts from a dictionary. Utilizing the built-in pop() methodology, you may simply delete a component primarily based on its given key. The syntax is:

dict.pop(key, defaultvalue)

The pop() methodology returns the worth of the eliminated key. In case of the absence of the given key, it would return the default worth. If neither the default worth nor the secret’s current, it would give an error. 

Right here’s an instance that reveals the deletion of parts utilizing dict.pop() –

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}
my_dict.pop("username")
print(my_dict)

The output is:

{’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

Appending component(s) to a dictionary

It’s straightforward to append parts to the prevailing dictionary utilizing the dictionary title adopted by sq. brackets with a key inside it and assigning a worth to it. 

Right here’s an instance:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict['name']='Nick'

print(my_dict)

The output is:

{‘username’: ‘ABC’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’, ‘title’: ‘Nick’}

Updating current component(s) in a dictionary

For updating the prevailing parts in a dictionary, you want a reference to the important thing whose worth must be up to date. 

On this instance, we are going to replace the username from ABC to XYZ. Right here’s how you can do it:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict["username"] = "XYZ"

print(my_dict)

The output is:

{‘username’: ‘XYZ’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

Insert a dictionary into one other dictionary

Allow us to think about an instance with two dictionaries – Dictionary 1 and Dictionary 2 as proven beneath –

Dictionary 1:

my_dict = {“username”: “ABC”, “e mail”: “abc@gmail.com”, “location”:”Gurgaon”}

Dictionary 2:

my_dict1 = {“firstName” : “Nick”, “lastName”: “Jonas”}

Now we need to merge Dictionary 1 into Dictionary 2. This may be carried out by making a key referred to as “title” in my_dict and assigning my_dict1 dictionary to it. Right here’s how you can do it:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict1 = {"firstName" : "Nick", "lastName": "Jonas"}

my_dict["name"] = my_dict1

print(my_dict)

The output is:

{‘username’: ‘ABC’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’, ‘title’: {‘firstName’: ‘Nick’, ‘lastName’: Jonas}}

As noticed within the output, the important thing ‘title’ has the dictionary my_dict1. 

Fast Packages on Python Dictionary Append

1. Restrictions on Key Dictionaries:

Python dictionaries have some restrictions on their keys. Listed here are some examples of invalid dictionary keys:

bashCopy codemy_dict = {[1,2]: 'worth'}  # Lists are unhashable and can't be used as keys
my_dict = {{1:2}: 'worth'}  # Dictionaries are unhashable and can't be used as keys
my_dict = {'a': 'value1', 'a': 'value2'}  # Duplicate keys are usually not allowed in dictionaries

2. Find out how to append a component to a key in a dictionary with Python:

You possibly can append a component to an inventory that may be a worth related to a key in a dictionary like this:

cssCopy codemy_dict = {'key': [1, 2, 3]}
my_dict['key'].append(4)
print(my_dict)  # Output: {'key': [1, 2, 3, 4]}

3. Accessing parts of a dictionary:

You possibly can entry parts in a dictionary utilizing their keys like this:

bashCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
print(my_dict['key1'])  # Output: 'value1'

You can too use the get() methodology to entry dictionary parts. This methodology returns None if the secret’s not current within the dictionary:

bashCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
print(my_dict.get('key1'))  # Output: 'value1'
print(my_dict.get('key3'))  # Output: None

4. Deleting component(s) in a dictionary:

You possibly can delete a component from a dictionary utilizing the del key phrase like this:

cssCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
del my_dict['key1']
print(my_dict)  # Output: {'key2': 'value2'}

5. Deleting Component(s) from dictionary utilizing pop() methodology:

You can too delete a component from a dictionary utilizing the pop() methodology. This methodology removes the key-value pair from the dictionary and returns the worth:

goCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
worth = my_dict.pop('key1')
print(my_dict)  # Output: {'key2': 'value2'}
print(worth)  # Output: 'value1'

6. Appending component(s) to a dictionary:

You possibly can append a brand new key-value pair to a dictionary like this:

cssCopy codemy_dict = {'key1': 'value1'}
my_dict['key2'] = 'value2'
print(my_dict)  # Output: {'key1': 'value1', 'key2': 'value2'}

7. Updating current component(s) in a dictionary:

You possibly can replace an current component in a dictionary by assigning a brand new worth to its key like this:

cssCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
my_dict['key2'] = 'new_value'
print(my_dict)  # Output: {'key1': 'value1', 'key2': 'new_value'}

8. Insert a dictionary into one other dictionary:

You possibly can insert a dictionary into one other dictionary by utilizing the replace() methodology like this:

bashCopy codemy_dict1 = {'key1': 'value1'}
my_dict2 = {'key2': 'value2'}
my_dict1.replace(my_dict2)
print(my_dict1)  # Output:

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