The right way to Add Key/Worth Pair

Python dictionary is a set sort that shops knowledge in key-value pairs. It’s unordered, changeable, and doesn’t permit duplicates. Dictionaries are very environment friendly for trying up and inserting knowledge, as they use a way known as hashing to map keys to their related values. They’re a strong knowledge construction that lets you retailer and manipulate knowledge in a key-value pair format. One frequent activity when working with dictionaries is to append new values to an current dictionary. Whereas Python dictionaries would not 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 put up, we’ll discover a few of these strategies and talk about when to make use of every one. So, let’s dive in!

Dictionary in Python

A dictionary is a crucial knowledge sort in Python programming. It’s a assortment of information values which might be unordered. Python dictionary is used to retailer objects wherein 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 just used so as to add key/worth to the present dictionary. The dictionary objects are mutable. Not like different objects, the dictionary merely shops a key together with its worth. Due to this fact, the mix of a key and its subsequent worth represents a single aspect within the Python dictionary.  

Restrictions on Key Dictionaries

Under are enlisted some restrictions on the important thing dictionaries –

• A given key seems solely as soon as in a dictionary. Duplicates of keys aren’t allowed. 
• It gained’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 might be thought of.
• If a secret is specified a second time after the creation of a dictionary, then the second time might be thought of as it would override the primary time.
• The important thing should be immutable, which means the information sort could be an integer, string, tuple, boolean, and so forth. Due to this fact, lists or one other dictionary can’t be used as they’re changeable.  

The right way 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 components is positioned inside curly brackets, and key: values are separated by commas. It should be famous that the worth of keys could be repeated however can’t have duplicates. Additionally, keys ought to have immutable knowledge 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 using Integer Keys: ")
print(Dict)
  
# Making a Dictionary
# with Blended keys
Dict = {'Identify': ‘Nice Studying’, 1: [1, 2, 3, 4]}
print("nDictionary with using Blended Keys: ")
print(Dict)

The output is :

Dictionary with using Integer Keys: 

{1: ‘Studying’, 2: ‘For’, 3: ‘Life’}

Dictionary with using Blended Keys: 

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

Dictionary with integer keys

Right here’s tips on how to 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.objects():
    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 components of a dictionary

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

Right here’s an instance –

# Python program to reveal
# accessing a component from a dictionary
  
# Making a Dictionary
Dict = {1: 'Studying', 'identify': '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

Various methodology 

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

Right here’s an instance –

# Making a Dictionary
Dict = {1: 'Studying', 'identify': '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 aspect(s) in a dictionary

You may delete components in a dictionary utilizing the ‘del’ key phrase.

The syntax is –

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

Use the next syntax to delete your entire dictionary –

del my_dict  # it will delete the dictionary with identify my_dict

One other various 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 verify an instance of the deletion of components that end in emptying your entire dictionary –

my_dict = {"username": "ABC", "electronic 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:

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

{}

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

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

    print(my_dict)

NameError: identify ‘my_dict’ just isn’t outlined

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

The dict.pop() methodology can also be used to delete components 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 is current, it would give an error. 

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

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

The output is:

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

Appending aspect(s) to a dictionary

It’s simple to append components to the present dictionary utilizing the dictionary identify adopted by sq. brackets with a key inside it and assigning a price to it. 

Right here’s an instance:

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

my_dict['name']='Nick'

print(my_dict)

The output is:

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

Updating current aspect(s) in a dictionary

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

On this instance, we’ll replace the username from ABC to XYZ. Right here’s tips on how to do it:

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

my_dict["username"] = "XYZ"

print(my_dict)

The output is:

{‘username’: ‘XYZ’, ’electronic 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 under –

Dictionary 1:

my_dict = {“username”: “ABC”, “electronic 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 finished by making a key known as “identify” in my_dict and assigning my_dict1 dictionary to it. Right here’s tips on how to do it:

my_dict = {"username": "ABC", "electronic 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’, ’electronic mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’, ‘identify’: {‘firstName’: ‘Nick’, ‘lastName’: Jonas}}

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

Fast Applications on Python Dictionary Append

1. Restrictions on Key Dictionaries:

Python dictionaries have some restrictions on their keys. Listed below 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 aren't allowed in dictionaries

2. The right way to append a component to a key in a dictionary with Python:

You may append a component to a listing 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 components of a dictionary:

You may entry components in a dictionary utilizing their keys like this:

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

You may also use the get() methodology to entry dictionary components. This methodology returns None if the secret is 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 aspect(s) in a dictionary:

You may 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 Factor(s) from dictionary utilizing pop() methodology:

You may also 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 aspect(s) to a dictionary:

You may 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 aspect(s) in a dictionary:

You may replace an current aspect 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 may 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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